Slot A Mainboards Comparison

by FastSite
12/03/1999 | 12:00 AM

Over three months have already passed since the first AMD Athlon processors, which are rightfully regarded as the fastest x86 processors nowadays, appeared in the market. We can already enjoy a couple of different Athlon models, however, the main problem about assembling an Athlon based system is still the proper mainboard you have to choose. As is known, AMD refused to use Intel GTL+ system bus and its new processors work with EV6 licensed from DEC. That is why Athlon requires special mainboards equipped with Slot A.<%BANNER[article]%>

There are not so many of them currently available in the market:

• ASUS K7M
• BIOSTAR M7MKA
• FIC SD11
• Gigabyte GA-7IX
• Microstar MS-6167

The thing is that Intel tries to put pressure upon those mainboard manufacturers, who support AMD and start making Slot A mainboards. Namely Intel very often delays the chipsets supplies to these companies, that's why the new members are not so frequently added to Slot A mainboard family. Moreover, to avoid persecutions most mainboard manufacturers do their best to keep their Slot A products from Intel. Therefore they grant these products no support and supply the mainboards in differently looking or even white boxes.

Of course, having launched its Athlon AMD made a serious mistake - they neither started making the mainboards for their new CPU nor bought any reliable manufacturer. That's why things are as they actually are.

But let's return back to our boards. All of them are based on AMD 750 (Irongate) chipset since there is not much to choose from, actually. The features of this chipset are very similar to those of the good old i440BX probably with the only major exception: EV6 system bus support, which is so important for Athlon. EV6 is a high performance bus working at 100MHz as well. However, unlike GTL+, in EV6 the data is transferred along the two fronts of the signal. That is why the real data transfer frequency makes 200MHz. And as for the rest, Irongate's features as well as those of the graphics cards based on this chipset are quite common: AGP 2x support, up to 768MB PC100 SDRAM memory and up to 6 PCI-devices. The mainboard manufacturers usually provide their products with the AMD-751 North bridge combined with either AMD-756 or VIA 686A as a South bridge. Both controllers support Ultra DMA/66, 4 USB ports and other standard functions. However, the main advantage of VIA 686A South bridge over that from AMD is first - an integrated AC'97 codec supporting software modem and sound card and second - a built-in hardware monitoring controller.

Unfortunately, the only existing chipset intended directly for AMD Athlon doesn't support a faster AGP 4x mode as well as PC133 SDRAM. But the situation is expected to change for the better in the near future: the market should soon welcome a series of new mainboards based on VIA's new Slot A chipset - KX133, which supports these two features as well as all the rest. By "all the rest" we mean here a possibility to process the CPU signals in a slightly different way, which allows significantly simplifying the mainboard design. This is exactly the fact that should help a great number of mainboard manufacturers to arrange the production of stable and reliable Slot A mainboards. In fact, we expect the first VIA KX133 based mainboards to appear after the New Year.

And in the current article we are going to speak about the mainboards, which are currently available. Here is a list of their basic features:

And now we would like to say a few words about every mainboard from the list.

ASUS K7M

ASUS engineers developed this mainboard on their own that's why it doesn't have anything in common with the Fester reference-design suggested by AMD. The main difference is the fact that ASUS K7M is the only 4-layer Slot A mainboard available in the market right now, all the others are 6-layer ones. This design peculiarity not only allows increasing the mainboard's stability but also reduces manufacturing expenses. For the South bridge K7M has VIA VT82C686A microchip, which allows to install an AMR slot and to integrate the software AC'97 sound redirecting some work to the CPU. However, the hardware monitoring of VIA 686A is not involved for some reason and it is carried out on a WinBond W83782D controller. The mainboard is equipped with 3 fan connectors, 1 built-in temperature sensor and 2 thermistor connectors. Besides, there is also a case open detector.

ASUS K7M is the only mainboard of all tested, which can boast rational overclocking features. It is possible not only to increase the system bus frequency, which can be done either with the help of dip-switches or through BIOS Setup, but also to change the CPU core and I/O (memory, PCI, chipset and AGP) voltage. Unfortunately, there are no functions for processor multiplier resetting, which is actually not a surprising thing, because it is hardware fixed in AMD Athlon. By the way, BIOS Setup also includes options for memory timings fine tuning.

Voltage regulators of this mainboard are covered by a massive originally shaped heatsink. However, we can't say that they heat so greatly, in fact, and the mainboard works normally even without this heatsink.

ASUS decided not to spare on the mainboard capacitors that's why according to our tests ASUS K7M proved not only the fastest but also the most stable and reliable board of all. And the 4-layer design contributes to it as well. Despite ASUS recommendations to use K7M only with 250W power units it works well with 235W power supply units as well even if the elder AMD Athlon processors are installed, which is unfortunately irrelevant with respect to all the other testing participants.

The mainboard is supplied in a masked badgeless box and the marking on the PCB is painted over.

BIOSTAR M7MKA

The mainboard is based on a 6-layer AMD Fester reference design. It seems to be the worst reference design copy of all we had. In particular, there are only 2 connectors for external fans. Flash-memory microchip is soldered into the board instead of being installed in a usual socket. So, in case BIOS gets damaged during reflashing, for instance, you can simply throw the mainboard into garbage. For some reason the supply doesn't include Ultra DMA/66 IDE-cable but in return you can see Norton Antivirus and Norton Ghost among the provided software.

But the most unpleasant thing about BIOSTAR M7MKA is stability problems when working with elder processor models. During the tests Athlon 650 worked more or less satisfactory only if we used a 250W power supply unit, and Athlon 700 didn't work even with a 300W one.

Unfortunately, BIOS Setup can't boast any options for system fine tuning. The manufacturers probably did it this way because the major part of these mainboards is supplied to the OEM PC assemblers, who usually don't feel like allowing the users to be free to set their PC parameters to their own taste.

FIC SD11

Like ASUS K7M mainboard, this one was also developed by FIC engineers absolutely independently. However, we can't say that the results they managed to achieve were as brilliant as those achieved by ASUS. Similar to Fester, FIC SD11 has a 5-layer design although it is of much bigger size. In fact, SD11 is a full-size ATX board, which makes it unfit for a number of PC cases.

The South bridge is made by VIA 686A chipset, however, AC'97 codec features are not used at all. Though they use the integrated hardware monitoring. Besides, the mainboard is equipped with only 2 fan connectors and the temperature sensor is for some reason placed behind Slot A.

As for the voltage regulators, there are only 4 of them installed though initially there can be 8 (the places for them are provided). In other words, all these things together with a giant size result into unstable performance with some power sources, especially those of lower power. In fact, only with a 250W power supply unit the mainboard proves more or less normal. But nevertheless, according to the info posted on AMD web-site, you'd better refrain from using your SD11 with a 700MHz Athlon at all.

But this is not all. Besides, FIC SD11 has a lot of other strange peculiarities. First, this mainboard has only 1 COM-port, and second, the external connectors lack the so dear colored marking. That's why the supply also includes a special back panel for ATX-cases without which the mainboard can't be installed.

SD11 BIOS Setup is provided with the functions of memory timings fine tuning and system bus frequency changing. However, the only supported non-standard frequencies - 120 and 130MHz - are very unlikely to be really used in practice, that's why we can take this board as the one without overclocking support.

Gigabyte GA-7IX

This is another mainboard based on the reference design. GA-7IX doesn't have any specific features except the absence of heatsinks on the voltage regulators. However, with the existing Athlon models they do not heat so much even without heatsinks, though we cannot guarantee that they will keep on like that with the future CPUs as well.

The mainboard has 3 fan connectors and is provided with 3 thermistors and a case open detector.

One of the Fester reference design major drawbacks present in this board too is the location of DIMM slots very close to AGP. As a result, this inconvenient location prevents you from installing and removing DIMM modules when the graphics card is installed into AGP-slot. By the way, although BIOSTAR M7MKA is also made after the same Fester design, it is deprived of this drawback, because its DIMM slots possess much smaller clips.

According to the testing results, GA-7IX proved highly stable though it can't boast any super fastness. It is probably due to a large number of capacitors on the PCB. As well as the mainboard from ASUS, this board performed well with elder Athlons when we used 235W power supply unit, although the AMD site didn't advise to use this board with Athlon 700.

There are special options for memory fine tuning in BIOA Setup.

Like ASUS, Gigabyte carefully hides the origin of this mainboard supplying it is an untypical badgeless box.

Microstar MS-6167

This was the first mainboard based on AMD Fester reference design that appeared in the market. As in the previous case, it doesn't have any special features except the absence of hardware monitoring.

Although the voltage regulators are equipped with the heatsinks, MSI decided to save a bit on the capacitors and provided its mainboard with much fewer capacitors than the previous board. And the outcome of this economizing didn't keep us waiting for long: MS-6167 appeared very unstable.

The mainboard is provided with 3 fan connectors and BIOS Setup is very similar to that of Gigabyte GA-7IX and allows memory timings fine tuning. And the above mentioned problem with the DIMM modules installation if the AGP graphics card is not removed exists by this mainboard as well.

Performance

The testing system we used for Slot A mainboards testing was configured as follows:

• AMD Athlon 650 CPU
• Chaintech Desperado AGP-RI40 graphics card (NVIDIA Riva TNT2, 16MB SDRAM)
• Creative Sound Blaster Live! sound card
• IBM HDD IBM DJNA 372200
• 128MB PC100 SDRAM by SEC (CAS2)

Since the performance of the systems on different mainboards based on one and same chipset hardly differs we are not going to stuff our comparison with the whole bunch of different tests. The main thing for every mainboard is stability and reliability, which has been already described above.

To check the systems' performance in the usual office applications we used Winstone99:

The winner here is ASUS K7M mainboard.

Then, we tested the performance with one of the latest gaming applications Quake3 v.1.09. We used the integrated demo - demo002.

As we see, ASUS K7M is again the leader and this time it has left everybody very far behind. Once again ASUS proved the manufacturer number one of the impeccable, stable, reliable and very efficient products.

Overclocking

Here we are not going to touch upon AMD Athlon overclocking when the locked clock multiplier is changed, because in this case we will have to open the processor cartridge and to resolder some inner elements. We suggest taking a look at the overclocking opportunities offered by the mainboards we had at hand.

The only possibility to overclock AMD Athlon without any interference with the processor cartridge interior is by means of FSB frequency increase. Only two mainboards of all tested can boast these features: ASUS K7M and FIC SD11.

ASUS K7M allows setting an impressively wide range of FSB frequencies: 90, 95MHz, any value from the interval between 100 and 125MHz and also 133, 140 and 150MHz. FIC SD11 supports only three frequencies: 100, 120 and 133MHz. However, our experience showed that this abundance remains undemanded. We tried to overclock a few CPUs working at 600 and 650MHz with the help of FSB frequency increase, however, in all cases the maximum frequency for the system to perform normally was only 110MHz. This gave us every reason to believe that it was not the CPU that limited the overclocking but something else such as the chipset or the system bus for instance. This conclusion got another proof from the fact that unlike GTL+, EV6 bus used in Athlon mainboards transfers the data along both fronts of the signal, which automatically implies a twice as high data transfer rate than that provided by GTL+, and hence it doubles the chipset utilization.

So, EV6 bus appears overclocking unfriendly. That is why AMD Athlon can overclock up to much higher speeds with the help of the changed clock multiplier.

As a result, it turns out that the additional frequencies provided by FIC SD11 cannot be used at all, while ASUS K7M still gives us a chance to slightly overclock the board.

We measured the performance of the system based on ASUS K7M with the AMD Athlon 650 CPU working at higher FSB frequencies. For our test we used Quake3 v.1.09 working in Fastest regime as the most processor dependent:

As we see, maximum performance gain achieved at 110MHz external frequency makes 10%, which approximately corresponds to the performance of the non-overclocked AMD Athlon 700.

Recommendations

Unfortunately, we have to admit that the situation with AMD Athlon mainboards is not so beautiful. Besides, their simple lack in the market, we should also point out some problems with the power supply units of low power and with the stability of certain products. These problems are very likely to be connected with the 6-layer design of most Slot A mainboards, which needs to be very carefully manufactured and this is within the power of very few manufacturers.

This situation will probably improve in the near future as soon as we see VIA KX133, which doesn't necessarily require a 6-layer PCB, and besides the development of a new 4-layer AMD Shinner reference-design may also turn things for the better.

And for now the only thing we can recommend you is ASUS K7M - a perfectly stable product, which can also boast an incredible performance. Besides, this mainboard is overclockable. The only drawback of ASUS K7M is the absence of open support on ASUS web-site. And as for the new BIOS versions for this board, they are now available only on ASUS ftp server at the following addresses: ftp://ftp.asus.com.tw/pub/ASUS/mb/slota/ or ftp://ftp.asuscom.de/pub/ASUSCOM/BIOS/Slot_A/AMD_Chipset/AMD_751/K7M/ . The second mainboard providing more or less acceptable system performance is Gigabyte GA-7IX. However, this mainboard showed very poor results in the performance tests and AMD doesn't recommend using it with 700MHz CPUs.

As for the rest, we wouldn't advise you to purchase any of them because they prove very unstable and arouse too many problems if the power supply unit is of lower power than it should be.