Posts Tagged ‘Mainboard

12
Nov
18

Mainboard: AOpen MX3W

Today I’m looking at a Socket 370 made by AOpen around mid 1999. It’s a clearly budget board as we will see when taking a closer look. I referenced this contemporary Anandtech article whilst writing this. I’m trying out a different device for taking the overview photos today as my old camera has seen better days. Let us begin with a shot of the whole board.

The first obvious thing is the mATX form factor and the lack of an AGP slot. So this was definitely not intended for the gaming or high performance market. It sports an Intel 810-DC100 chipset with the basic on-board video, and an AD1881 soft audio codec for sound. The chipset is interesting as it has the FSB and memory clocks separate. The memory will run at 100Mhz at a maximum, whilst the FSB can achieve speeds well in excess of this. This board can increase the FSB speed but the RAM clock cannot be changed. This means that any overclock could only be effective up until the point the memory bus becomes saturated, at which point overclocking any further would not increase performance.

Cache SRAM chips

The on-board graphics are fairly basic, it’s roughly equivalent to the Intel i740, a GPU that was never known for being particularly fast. It uses the system memory for much of the work involved in 3d rendering, which obviously consumes memory bandwidth the CPU could potentially require. To mitigate this flaw a 4MB cache was added to this version of the chipset, it is used mostly for storing the Z-buffer. I’d imagine this makes a fair difference whilst rendering 3d images, but doesn’t entirely solve the problem.

The on-board sound solution is similarly very basic. It’s an AD1881 audio codec, which Anandtech described as a “soft” audio device. By this they meant that much of the processing work for audio is done by the host CPU rather than specialised hardware on the sound chip. This is much like early sound cards which relied on the CPU for mixing audio channels together as the hardware only played back a stream of samples. At the time this board was made there were plenty of more advanced sound chips available that could do everything in hardware, some even turned up as integrated sound.

In terms of performance this board wouldn’t be all that good compared to the higher end. However that’s not what it was really designed for. For basic use such as office work and web browsing this would have been adequate for the time.

From a technicians point of view there are a few issues with this board. Firstly, there isn’t much variability in how you can build a system with it, only budget machines are really possible. The on-board graphics does not perform well and there is no AGP slot for an upgrade. There are only two memory slots which are limited to 100Mhz RAM, so you’re quite limited in how much and how fast the memory can be. Finally the floppy connector is in an odd spot near the AMR slot, this results in running a ribbon cable across the board which is generally bad for air flow in the case. My particular example is further hampered by one of the memory slots having a broken retaining clip.

For the end user it would probably perform well for most basic tasks, but get bogged down when they do something requiring a little more grunt. The lack of upgrade options would probably be an issue for some depending on what their needs are. Given that it’s a budget model none of this should be surprising, only people looking for a low price would have found this appealing.

29
Jun
18

Motherboard: MSI 970A-G43

I had almost ran out of old motherboards for this section when my brother gave me this particular board. He gave it to me as he had upgraded to a Ryzen based system and this one had failed. Unlike the others so far this one is actually relatively modern, although by no means current as it is at least about 4-5 years old. It’s not really remarkable in any way, but it has many typical features of modern boards I’ve not yet discussed.

Here’s a picture of the board.

It’s an AM3+ socket board with an AMD 970 + SB950 chipset which was fairly middle of the road performance wise when it was new. Part of the reason for this came down to AMD not having a competitive CPU on the market at the time, this was well before the Ryzen chips had launched. Lets look at some of the features of the board.

Most peripherals that you could need are integrated, with the exception of the graphics card. There are plenty of USB connectors on the back as well as in header form, although only a few of them are USB3. The on-board SATA controller offers basic RAID capability, and the audio chip is adequate but neither are as good as dedicated cards at their job. Like earlier boards, part of the issue is the location of the audio chip, with it being located near the bottom of the board. This increases the chance of noise and crosstalk affecting audio quality. The LAN chip supports up to gigabit speed as you’d expect.

Like most modern motherboards support for most legacy hardware has been dropped with a few exceptions. There are two PCI ports for old expansion cards, a serial port header, and surprisingly PS/2 ports for keyboard and mouse. With the wide spread use of USB for keyboards and mice these days it’s a little odd to still see old school PS/2 ports.

A big change over older boards is the move away from electrolytic capacitors towards solid polyester capacitors. There are lots of benefits arising from this change, the best of which is the increased lifespan and durability. The downside seems to be increased cost, as there are more capacitors, but I think the trade off is totally worth it. Here you can see the voltage regulation circuits for the CPU, it appears for each voltage there is two caps, 4 FETs and an inductor. Nearby are a further 7 capacitors which could be more bulk capacitance for the voltage regulation, but could also be for the nearby USB ports. Also note the board has marking and holes for a heatsink, but in this instance one is not fitted.

Modern boards don’t really use jumpers for configuration any more, but the front panel header still needs a nice clear silkscreen label. Unfortunately MSI could have done better with this particular board, there are two headers relevant to the front panel, both have labels, but they are both a bit hard to read. If you were handling many of the same board this wouldn’t be a huge issue as you’d learn the layout, but it would be a bit of a pain the first few times. Otherwise there aren’t any issues that make it hard to install or maintain.

This board would be a reasonable choice for many end users who only use their machines for basics such as web browsing and email. My brother used it for lighter gaming loads such as minecraft, which it handled reasonably well with a decent GPU, however it was never suitable for heavier games that are more processor intensive. Being relatively young it’s not really suitable for a retro PC as there is no support for an older OS available.

19
Oct
17

Motherboard: EPoX EP-8K3A

Today’s motherboard is a Socket 462 board (also known as Socket A) it is an EPoX EP-8K3A made in early 2002. The CPUs that fit this socket type have an exposed die that makes direct contact with the heat sink, this is generally good for heat dissipation, but makes installing or removing a heat sink a risky business. Here’s a photo of the board.

The board has a VIA KT333 chip-set, which at the time was one of the first to support the then new DDR333 standard. VIA chip-sets were very common at the time, especially where AMD CPUs were installed. An interesting feature was it’s ability to run the memory and FSB clocks asynchronously, although in practise this wasn’t that useful. If the memory was slower it became a bottle neck for the entire system. If it was faster the CPU wouldn’t have been able to make full use of the extra bandwidth, although that bandwidth could be used by other devices such as a graphic or sound card. Also noteworthy is the fact that this is a single memory channel board, later systems made use of the dual channel architecture which had a memory bandwidth advantage.

It has the usual suspects as far as peripherals go. It has a HDD/FDD controller, Serial/parallel ports, two USB ports, AC97 audio and a game port, which would have covered most users needs at the time. It lacks on-board LAN and USB 2.0, which would have been nice to have, but are easily added via the 6 PCI slots. There were two models, one had extra IDE ports connected to a RAID controller along with a diagnostic module that displayed the status on a two digit seven segment display. I have the board without these extra features, which doesn’t worry me as I can add a RAID card if needed.

EPoX was known for making boards for the enthusiast and over-clocker, and this board doesn’t disappoint on that front. You can see the voltage regulation circuitry has more capacitors and chokes than contemporary boards. They called this three-phase, but that’s not really a good description, basically it has three separate voltage regulator circuits just for the CPU core voltage. This results in a power supply with less noise on the line, and with the larger capacitor bank it also handles spikes in workload/power drain better. It probably increased the boards reliability over the long term, even if you didn’t over-clock. I found a review of the board that was written at the time it was released that has more details.

By the time this board was made jumpers were mostly a thing of the past, with everything under software control in the BIOS settings generally. With the front panel connectors clearly marked this board would have been quite easy to install and set up for an end use. This board would have been favoured by technicians partly because of this, but also because it would have almost certainly been more reliable, was fairly cheap, and was even forward compatible with processors and RAM that was yet to be released.

For end users this would have been a great work horse board for anyone, it is cheap, reliable, and has extensive upgrade options. However now as an old board, there are better socket A boards from the era with more features, better compatibility and faster chip-sets more capable of over-clocking. It would still be good in a vintage PC build, but not for a high performance machine of the era.

24
Aug
17

Motherboard: Another unknown Socket 3

Today I’m looking at another 486 socket 3 motherboard that unfortunately I can’t identify. Unlike the last one, this one actually had it’s model number on the silk screen, but the OEM who put it into a machine has covered the silkscreen label with either white paint or white out so that it is unreadable. Obviously this is a massive pain as I have no chance of finding a manual for this board, which is needed because of the large number of jumpers. I suspect they didn’t want end users finding out that it was a low quality board. Here’s a photo.

Again it’s a later 486 board as it has PCI slots rather than VLB slots. Reading the date codes on the chips reveals it was made in mid 1995, around the same time as the other socket 3 I have. The chipset was made by UMC, which I’m unfamiliar with. After having done some forum lurking over at VOGONS and reading some of the Red Hill Guide, it seems that it’s a fairly common chipset found on a variety of boards. I can’t comment on the performance myself, but others have had success getting decent performance out of their chipsets.

There are very few integrated peripherals, it has an old school DIN keyboard connector and two IDE ports, but strangely no floppy disk controller, serial or parallel ports. This ultimately wouldn’t have saved much money for the end user as they’d have to use add in cards to replace the functionality. Weirdly the IDE ports each use different styles of socket, another sign of cheapness.

The cache chips and system ROM are all socketed, which is a good sign that the cache is probably not a fake. The EPROM unfortunately had the sticker missing, exposing the window for the UV erasable chip. I’ve since put my own sticker over the window to protect it.

In an effort to identify it, I decided to pull the ROM chip and read it in my TL866 universal programmer. I was hoping to find a string that had the model name in it directly,but after an extensive search I only found the BIOS version string, “2A4X5B05”, which was enough to identify the manufacturer as Biostar but not the model.

Another unfortunate feature of this board is this real time clock chip with integrated battery. The idea is great in theory, but results in an unusable board when the battery runs flat, which it has.  Some of these RTC chips had the option of an external battery, unfortunately this isn’t one of them, so the only option I have is to either replace the chip (it’s not socketed) or hack it open and attach an external battery. Unfortunately this board doesn’t even remember the settings through a warm reboot, preventing it from actually booting an OS.

Like many 486 boards much of the basic configuration is done with jumpers. This usually means looking them up in the manual, but this board does have the basic settings for voltage, FSB speed and L2 cache size. Still there are obviously many more jumpers that are undocumented on the board, so the manual would be really handy. Luckily the silk screen has enough information you could install a CPU and not make the magic smoke escape.

At the time this board was made it was fairly low end, and windows 95 was just around he corner. It would have probably performed ok with MS-DOS and Windows 3.1, but would have been inadequate for Windows 95 when it came out later the same year. Most 486 machines didn’t really perform well with windows 95 so that’s hardly a surprise. The lack of integrated peripherals is probably the worst point with this particular board, as you’ll need add-on cards even for basics such as a floppy drive and serial port (which you’ll need for a mouse). Otherwise it would have made a serviceable, but not powerful machine.

05
Apr
17

Motherboard: Aopen AX34-U

I’ve been rather busy of late, and it’s been raining here in buckets, so finding the time for photographing a board has been tricky. In any case I had some time today and have found a socket 370 board made by Aopen.

I wasn’t able to decipher the date of manufacture from any of the date codes on the board, but it’s almost certainly made around the early 2000’s. It supports the Tualatin and Coppermine cores of the Pentiun III and Celeron chips. The Coppermine ones had a reputation of being quite good at over-clocking at the time.

Looking at the board as a whole the layout is pretty standard for the time, although I’m puzzled as to why the AMR slot is right next to the AGP slot. I’ve never seen an AMR card in the wild, probably because they were pretty poor software modems. On this board it occupies what would be a prime spot for a PCI slot, which I’d much rather have.

You’ll also note it still has a legacy ISA slot, something which disappeared from consumer hardware in a few short years around the time this board was made. ISA slots stuck around for a surprisingly long time, partly due to the amount of hardware that was made for it. It was used for many unusual cards some for controlling industrial machines. I have one somewhere that was used as a lighting controller for dance floor lighting in a pub. Machines made for industrial conditions kept the ISA slot for much longer.

Unfortunately this board seems to have suffered leaky caps, a common cause of failure for many electronics. One has coated a surrounding chip with it’s goo. This kind of problem can be repaired, but it isn’t usually done because of the time or cost involved if you pay someone to do it. If you have the time, patience and skill you can clean up the goo and replace the caps, often restoring the device to functionality. I’m not confident I can repair this yet, as my soldering skills are pretty much hobbyist level. It’s easy to damage a board like this as it has very fine traces and small pads designed for machine assembly.

Performance wise this would have been quite a nice piece of kit. It has a VIA Apollo Pro 133T chipset which was a reasonable performer as well as being cheaper than alternatives. It had room for 1.5Gb of RAM providing you used the expensive-at-the-time 512Mb modules. With only 3 SDRAM slots you couldn’t use many of the cheaper sticks to make up the difference, but few people were going for more than 0.5Gb of RAM at the time.

From a technicians point of view it’s fine in terms of specs, but the board silk-screen isn’t as helpful as others when connecting the front panel and setting jumpers. The front panel is marked, but isn’t real easy to read, which can be worse in the tight confines of a case. Luckily there aren’t too many jumpers as software controls much of the settings, most of the jumpers you won’t need to touch with perhaps the exception of the one that sets the FSB speed. The manual is also still available if you need further help.

As an end user this would have been quite a good buy, it has most things you need integrated (except NIC) and has a decent chipset with support for a decent range of configurations. You could build either a cheap and cheerful machine, or something with pretty good performance with a board like this one.

 

15
Sep
16

Motherboard: ASUS P4S800 MX SE

Today is another of my more modern mother boards, the ASUS P4S800. It was made late 2003, roughly half way through the life of the Pentium 4, which was starting to look old compared to the new AMD Athlon 64 processors that were released that year. This board is clearly designed for the cost conscious but still has an impressive feature set. Here’s an overview of the board.

My particular example has had a custom heat sink clip fitted, likely for a custom heat sink made for increased heat dissipation. That’s a little strange as it was later P4 processors that were known for using lots of energy and running hot. Unfortunately the clip is broken, but could be replaced with an original clip to get the board working.

CPU support includes 800Mhz FSB processors such as the Northwood, Williamette and Prescott cores. If you had a newer operating system such as Windows XP or Linux you could also take advantage of Hyper threading which essentially takes unused resources in a core and makes them available for use as a secondary logical core. To the casual user it looks like you get two cores for the price of one, however, if the primary core needs more of the processing resources the second one can get slowed down significantly as it gets starved of resources. It could also cause problems with the cache as both logical processors shared it and it consumed more power adding to the heat problems.

There is support for DDR400 which is as fast as that memory standard went. It does not support running the memory in a dual channel configuration, likely because there is only a single memory channel. Having only two memory slots is probably the most limiting part of this board as it would have meant a practical maximum of 1GB of for most users.

The chip set was made by SiS, which was known for making more of the budget parts. By this stage they had managed to sort out the driver and software problems that plagued earlier chip sets, so you can expect reliability from a board like this one. The chip set integrated graphics would have been ok for basic desktop use, but completely inadequate for much else. Luckily there is an AGP slot for adding your own GPU.

The P4S800 has quite a few integrated peripherals such as USB 2.0, SATA, LAN and audio. For a small form factor board this was basically necessary as there is little room for expansion slots in many mATX chassis which sometimes also require low profile expansion cards. It also has quite a number of useful legacy ports such as RS-232, parallel, and joystick ports (with a header).

img_2536Looking closely at the CPU voltage regulation there are a number of parts not populated on the board. The missing parts are filter capacitors and power transitors/MOSFETs. It’s not really a problem unless your processor requires lots of power. I wouldn’t put a Prescott core P4 processor in this board for this reason, as they have a much higher power demand.  It might work (or not), but would almost certainly shorten the life of the board.

Working on this board is fairly easy, almost all the jumpers are labeled quite well, and the front panel section is colour coded as well. Auto detection and software configuration (in the BIOS) take care of most configuration like modern motherboards. The only reason you would need the manual is to check the compatibility lists within for memory and CPU. Most of the integrated components are either integrated into the chip set or are Realtek devices, both of which are easy to get drivers for.

For the end user this board is very similar to the Aopen P4 board I’ve looked at before, only a little newer and faster. It probably wouldn’t suite someone looking for high performance, and may be have limited expandability depending on the chassis it is installed in. For general office/internet use it would probably have done the job, and would have been reasonably reliable providing the power regulator isn’t overly stressed.

20
Apr
16

Motherboard: MS-6153VA

Today I’m looking at a Socket 370 board that would have been made roughly in 1999-2000. It was an interesting period as much of the early legacy technology such as the ISA bus was fading out, marking the beginning of the end for complete backwards compatibility. It is also close to the end of configuring major component with jumpers, replaced with auto-detection and software control. Although this particular board still has a few jumpers.

It’s a MS-6153VA made by MSI, a manufacturer known for making  boards with gaming and over-clocking in mind. It seems they were one of the first to offer over-clocking as a feature quite early in the history of PCs. Surprisingly it was a 286 mainboard, a time when overclocking meant replacing the crystal oscillator. They still cater to the over clocking market with a series of boards dedicated to it.

Here’s an overview of my board.

IMG_2490

It’s remarkable because there are actually two boards with the same model number that differ significantly. This board has a VIA chip-set and is marked MS-6153, but if you search for that online you turn up a board that looks almost identical but has an Intel chip-set instead. The model number used in online references is MS-6153VA for the VIA chip-set. This must have caused some confusion at the time.

IMG_2492Here’s something different, 4 LEDs to indicate the current status of the system. If there was a problem they could use these instead (or in addition to) the standard BIOS beep codes. It wasn’t something you’d find commonly, but was extremely useful if you were lucky enough to have a visual indication. Some manufacturers took it further, using two 7 segment displays instead.

IMG_2493Like a previous Socket 7 board, this has a thermister mounted in the middle of the CPU socket. They’ve used a different package, a small flex with the component built in. I’m guessing they did this in an attempt to get a better reading closer to the CPU.

The chip-set is a VIA Apollo Pro 133A, which would have been quite decent for the time. Around the main chips are some of the reference silk-screen, which are quite handy, but are unfortunately quite distant from the jumpers they are a reference for! This may have been necessary due to the layout of the board, and I’m sure the manual would tell you where to find them, but it is annoying as it seems to effect every single silk-screen reference.

Speaking of the manual, I was able to find a download on the MSI website, however it was in the form of a EXE file! Since I’m using my Mac book I wasn’t able to easily open it, bad form MSI.

IMG_2497Next to the floppy connector is a connector that seldom got use in desktop machines. It’s an infrared header! Wireless technology had yet to really evolve into what it is today, and a cheap and simple technology commonly used was infrared, still used today in TV remote controls. It wasn’t commonly used mostly because IR (as it’s commonly called) relies on direct line of sight, and can easily be interrupted. These IR devices were usually treated as a serial port, so software like hyperterm was usable with them. In use they usually proved to be slower and less reliable than just using a cable.

From a technicians view-point it’s also fairly decent, it supported Intel and Cyrix chips up to 800Mhz which was decent for the time. It could also support the large 256Mb SDRAM sticks running at 133Mhz, allowing for a maximum of 768MB of RAM. There are also some rudimentary overclocking features on the board. The main annoyance is with the silk screen reference being so distant from the jumpers, and not having very descriptive names. Still, you could set this up without the manual.

Feature wise this board would have satisfied most end users, although audio and ethernet isn’t integrated. At that point in time integration hadn’t become the norm for those. Luckily there are plenty of PCI and ISA slots so it wouldn’t have been much of an issue. With the right CPU, RAM and GPU it probably would have even made a decent gaming rig for the time.

15
Mar
16

Motherboard: ASUS CUV4X-DLS

Today’s motherboard is one of the more unusual in my small collection, it’s a server/workstation board that takes two Pentium III class CPUs. Boards like this one were (and still are) quite unusual for the PC architecture, most only have one CPU socket to keep costs low and the complexity of the motherboard down. Dual CPU sockets were much more common on other architectures such as SPARC, MIPS, and PowerPC. I’d guess this particular example was for the server market as the game-port and on-board audio are not populated, although the foot prints are on the board and it has an AGP Pro slot so it may have been designed as a workstation board. I was given this particular board by a colleague who knew I like to collect old parts. It’s from a decommissioned server.

Here’s an overview of the board.

Here is something you didn’t normally see on socket 370 boards, an auxiliary power connector. This connector was also used later on early Pentium 4 boards, and is used here for a similar reason, to supply additional power. This would have been necessary in order to power the second CPU. Unfortunately this isn’t a common connector any more, so finding a power supply for a board with one of these can be difficult. Note there’s many capacitors on this board, and despite it’s age none appear to be bulging.

Another clue to this boards server origins is this, an on-board LSI Ultra SCSI controller. When this board was made SCSI was the go-to standard for server hard disks, mostly because of how much faster it was, but also because you could connect more disks to one controller. SCSI however was generally fairly expensive, so it usually didn’t make it to workstation or consumer level boards as those machines usually had cheaper IDE/ATA drives. Also note the very large power diodes very near to the SCSI port, quite an unusual feature!

Something I thought odd at first was the choice of a VIA chip-set, but thinking about it VIA made some of the better chip-sets of that era, often out-performing other manufacturers offerings. Later VIA became more known as a value chip-set, but this wasn’t until after Intel made significant improvements to their chip-sets.

Specification wise it supports Coppermine Pentium III up to 1Ghz and up to 4Gb of PC133 ECC(optionally) SDRAM. It’s unlikely that anyone would have actually installed the full 4Gb as the largest SDRAM DIMMs I saw in common service were 256Mb, although larger ones were available they were quite expensive until after DDR SDRAM became the norm. The graphics slot on this machine is an AGP Pro/4x slot which is also quite unusual. AGP Pro doesn’t actually extend the standard much, it mostly just provides more power to graphic card. They were beginning to require much more power, a problem which was later solved with a direction power connection on the graphics card. Luckily standard AGP cards will work quite happily in this board.

Here’s the memory I got with the board, it’s 256Mb 133Mhz ECC SDRAM made by a company called Viking. I’ve never heard of them before so the brand doesn’t inspire confidence, but usually memory of this type is of good quality and reliable. I have a total of 512Mb for this board.

I found the manual for this board fairly quickly but was surprised to not find it on the ASUS website. Not that you’d need it as the silkscreen has all the headers, DIP switches and jumpers described in detail including tables for setting the CPU speed. You only need to set the speed of the CPU manually if you wish to over/under clock them as the board is set for auto-detection by default. You’ll note that there is only one speed control for both the CPUs, this is because dual socket PC main boards require you use identical processors. Most technicians wouldn’t need the manual to work on this board.

I’m guessing this board saw very few end users being from a server, but for those that did use one as a workstation they would have likely used them at work in a CAD machine. With dual processors and the ability to use high-end workstation graphics this would have suited the task quite well with a few caveats. You would have had to use Windows NT (or it’s descendant Windows 2000) instead of Windows 9x as the later doesn’t support SMP. Neither Windows NT or Windows 2000 had as much support as the more consumer oriented Windows 9x series, so software and hardware support either cost more, or was simply non-existant. You could have also used a commercial Unix or a free one like BSD or Linux, which come with their own problems.

I used this board for some time running debian linux as a basic file server and web cache, it performed quite well at the time, but that was some time ago and I doubt a modern Linux distribution would run well now. It would probably suite running something like NetBSD which tends to require much less resources and can take advantage of the second processor. Last time I powered it on only one processor fan appeared to power up, I need to spend some time to determine if the power supply I have for it is the cuplrit or if this board has suffered some kind failure.

16
Feb
16

On-Board graphics

Most computer enthusiasts instinctively know that on-board graphics doesn’t perform as well as a discrete graphics card, but why isn’t common knowledge. Today I’d like to shed a little light on why this is.

However don’t take this as a criticism of on-board graphics, as they have their place within the industry to provide lower cost solutions for people who don’t need the ability or can’t afford the cost of a GPU card. AMD in particular have had some very nice graphics processors on-board or on-chip and their current line up of APUs does offer very good performance per cost.

I won’t be talking about any specific hardware, as there is just too much to cover. I’ll be talking about this in a more general sense.

Onboard graphicsHere’s a little diagram of how on-board graphics are usually connected to the main system memory and CPU. Where these components actually reside depends on the age of the system. Modern APUs contain everything in this diagram (and more) except the main system memory, older systems had the memory controller and GPU in the North bridge chip on the main board. Some older systems had a separate graphics chip that utilised the main system RAM, and others actually integrated some VRAM on the board. Boards with separate VRAM are completely different beasts, and actually have more in common with systems that have a discrete graphics card.

This story in fact starts off way back in the micro computer era of C64 and ZX spectrum, which essentially had integrated graphics. The graphics chips took up much of the memory bandwidth, essentially slowing down the machines CPU quite severely under certain conditions. Modern PCs with on-board graphics also usually share the system memory with the GPU, and this is where the performance hit usually originates from.

Firstly there is an un-avoidable loss of memory bandwidth in the form of video signal generation. All graphics processors have to actually output to a screen at some point, and this requires reading the entire frame buffer and outputting appropriate data to the screen. This is as true for HDMI and DVI as it was for old school CRTs, except the resolution and colour depth have increased.

Lets take an example, say 1920×1080 at 60Mhz with 32 bit colour. For every frame sent 8,294,400 bytes have to be read (the size of the frame buffer). Do this 60 times a second and you get 497,664,000 bytes per second or about 474.6 MB/s just to output to the screen. Whilst it’s not a huge chunk of the minimum 6400MB/s that DDR3 can deliver, it certainly will reduce the available memory bandwidth to the processor, lessening its potential performance.

On-board GPUs have a significant advantage in some areas, such as the CPU being able to write (draw essentially) directly to the frame buffer, and the GPU being able to read texture data directly from system memory. However this convenience isn’t all roses as we will see.

Lets consider a rendering situation, where the GPU needs to render a number of polygons into the frame buffer. To make it simple lets make the squares of 32×32 pixels (buffer size of 4Kbytes) and we’re going to render a number of them onscreen say 500,000 per frame, now you’re looking at copying 2,048,000,000 bytes which requires both a read and a write, so really in terms of memory bandwidth that’s 4,096,000,000 or about 3.82Gb.

This is a bit of a contrived circumstance, but you can see that it’s easy for a GPU to chew up memory bandwidth when it’s rendering. This can have the effect of starving the main CPU of memory bandwidth forcing it to run slower than it could have otherwise (and vice-versa). In practice that much bandwidth probably wouldn’t be needed as modern CPU and GPU designs incorporate caching, which works very well until you start dealing with data sets larger than the cache. In this case if we were copying the same bitmap repeatedly we could half the bandwidth required as the whole bitmap could be stored in the cache.

So how does this differ from a discrete graphics card?

Discrete Graphics CardHere’s another diagram showing how they usually fit in. The graphics card basically contains everything on the right, with the IO interface being the only means of communication with the computer.

Since the graphics card has its own memory the system isn’t burdened with output of the video signal. This graphic memory is usually dual ported, or in the case of modern GDDR5 which is capable of accessing two pages of memory simultaneously (effectively dual ported although only having one). This turns out to be important as it allows both the GPU and CPU to access the video memory at the same time, which reduces latency when writing to the video memory. This used to be a big problem with CGA, EGA and earlier VGA graphics cards that didn’t have dual ported memory and the CPU had to wait for the video signal to access the graphic memory.

This graphic memory also has the distinct advantage that when the GPU is rendering a scene it doesn’t slow down the main processor by consuming the system memory bandwidth.  It does however require the CPU to communicate via the IO bus to issue scene data and rendering commands. Most scene data (textures and meshes) are pre-loaded into the graphic memory so the load on the IO bus is minimised.

The only real disadvantages of the discrete graphics card are slightly increased loading times, and slower access to Graphic memory. Longer loading times arise from the need to pre-load the scene data to the graphic card, whilst the IO bus can be exceptionally fast, the logic in the graphic card and the speed of the system and graphic memory limit the throughput. There’s also usually lots of data to upload, in the realm of gigabytes these days.

I hope this goes some way to at least beginning to explain why on-board graphics as they are implemented now won’t achieve the same performance as a system with equal but separate parts. It’s mostly the fact that system memory is shared between the two that hampers both the CPU and GPU from achieving maximum performance. If in the future AMD or Intel were to change their chips such that the GPU on-board had its own separate bank of memory, you’d start to see on board graphics become more competitive with graphic cards. This would require either dedicated memory on the main board or an extra socket for it which would add to the cost, so I feel that would be unlikely. After all on-board graphics is all about reducing the cost.

05
Feb
16

Motherboard: Biostar M6TBA

Today’s motherboard is from a Taiwanese manufacturer called Biostar Microtech International (know as Biostar for short). They are one of the old guard of PC motherboard manufacturing having started in 1986, although until finding this board I haven’t used much or any of their hardware. In the past Biostar have made boards for OEMs as well as the high-end, mid and lower-end of the market. These days they seem to be focusing on higher end parts. This particular example is a M6TBA ver 1.3 which from the date codes on the board appears to be made in 1998.

Here’s an overview of the board.

Biostar M6TBA

It supports slot 1 processors up to 800 Mhz surprisingly, this would have been faster than any of the Pentium II chips available at the time. It was probably a forward looking design, perhaps with the capability to support a Pentium III in a slotket, although this isn’t documented in the manual. The slot 1 system was implemented by Intel for a few reasons, but mainly they wanted to move away from the ageing socket 7 standard, partly because it was limiting the memory bandwidth and partly because it was used by many of their competitors.

They initially designed another socket, which was called socket 8, this saw limited production as there was a problem with how the cache was integrated onto the CPU. It actually had two separate dies on the one package, which proved to be a production problem that increased wastage when either a cache die or processor die turned out to be faulty. The slot 1 design solved this problem by putting the CPU and cache in separate packages on an installable module. They did miss an opportunity to put the voltage regulation on the module, which would have made the slot 1 more flexible and future-proof.

The board is pretty standard fair for it’s time, having an Intel chipset ( 82243bx being the north bridge) with PCI, ISA and AGP slots, which were all fairly standard for the time. It supports up to 384MB of RAM in three 128MB SDRAM modules, which was quite alot of memory at the time. Many people had 64Mb-128Mb.

Front panelHere’s a close up of the front panel header and the CPU configuration jumper block (the ones with yellow jumpers). The front panel is marked, adequately,  but not really nicely. The CPU configuration block has no markings at all, requiring you to look up the manual, which luckily is still available. Looking at this block it is unclear what speed of CPU was installed, as according to the manual these settings don’t match any of the speeds. Perhaps the board can detect the speed automatically.

Heatsink footprint

 

An unusual feature of this board is the un-populated footprint next to the main power supply connected. It looks like a large heatsink was to be attached to the board with a linear voltage regulator, something you don’t normally see. It could be leftover from when the board was in the prototype phase, and thus not used in production, but still on the layout. Whatever the reason, the size of the heatsink foot print leads me to believe it was going to be dealing with a significant amount of power.

Speaking of power supply, check out the bulk capacitors next to the CPU slot.

Bulk capacitance

Some of the capacitors are visibly bulging, a sure sign they are failing. Sometimes a board will continue to function like this, but it usually means the board is about to fail. You can replace these components, but it’s tricky soldering on these multi-layer boards, it’s easy to damage them. It’s something I haven’t been brave enough to attempt yet.

SMC FDC37M602

Another interesting feature is this chip here, an SMC FDC37M602. It’s a Super IO chip which integrates floppy disk controller, serial ports, PS/2 ports and a parallel port. It’s quite some distance from the boards floppy connector, so I’d say the chipset is supporting that, at a guess I’d say this chip is driving all the rear port with the exception of the USB ports.

The thing I noticed however was the copyright notice on the chip, the date reads 1994 from a company called American Megatrends, a software house known for writing BIOS ROMs for PCs. This particular board however uses an Award BIOS which of course comes from a rival company! Not so much a technical achievement, but interesting to see.

Beginning to sum up this board, it’s not really ideal for the technician working on it. Mostly due to the CPU configuration jumpers having no markings at all. Otherwise it’s very similar to working on other boards of the same vintage. This would have been a more expensive board at the time, mostly because Intel boards and CPU’s tended to be more expensive. It has lots of standard slots allowing for upgrades and expansion. So it’s not all bad, just a bit inconvenient to change CPU with.




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