All of the above is a moot point (including the remaining issue with the command rate of the memory and the fact that I solved the video card problem by purchasing a GTX 285 or the excellent compatibility of nforce4 with SSD's )because:

B. VIA managed an excellent comeback on both socket 754&939 with K8T800 PRO. It proved to have the best performance out of all AGP platforms. Having proved superior to NVIDIA' nforce3 VIA set out to design a PCI-express chipset and the first one is K8T890. NVIDIA already proved by designing nforce4 that the first try can be a very successful one so now is VIA's turn.
Unlike nforce4 K8T890 is a classic northbridge/southbridge design. Usually that means more freedom as you can match them any way you want unlike the single chip nforce4 that is practically "set in stone". The northbridge is the new part while the southbridge is the true and tried VT8237!

VT8237 unfortunately has the infamous problem with SATA protocol version negotiation so new magnetic drives or SSDs won't work. It's a major downside. PCIe X1 SATA card will be necessary to make it usable. Not a problem with AGP boards intended for Windows 98.

There is ABit AX8 selling locally with VIA K8T890 + VT8237.

I think we will have to admit that in the end s939 works best with 2x 1GB sticks as then we can use CR 1T. In s754/s939 we need every drop of performance for Windows XP era as these platforms have low clocks.

I use CR 2T in my AM2+ system but only because it serves Windows XP/Vista/7 era so badly needs 8GB RAM. It also limits memory speed to DDR 800. It is less punishing as we have fast 4 cores that make up for the latency. It is suboptimal and I only use it that way because s754 already covers most of Windows XP.

To max out these systems I believe we should use:
s939 - X2 Toledo CPU, 2GB RAM (2x 1GB) DDR 400, CR 1T, Windows XP era. Small swap file is necessary (mostly unused). A few lucky owners can use 2x 2GB registered memory clocked at DDR500 and turn off swap file.
AM2 - X2 Windsor CPU, 4GB RAM (2x 2GB) DDR2 1066, CR 1T, Windows XP era - not powerful enough for full Windows Vista era
AM3 - X4 Phenom II CPU, 16GB RAM (2x 8GB) DDR3 1600, CR 1T, Windows Vista/7 era

Don't buy until you can get a clear look at the revision!!
Abit manufactured a single design named AX8. By providing extra controllers or extra hardware we got 4 models: AX8-V which is the basic model that comes with only what the chipset offers; AX8 that comes with an extra controller also from VIA - VT6421 with 2 SATA ports and 1 IDE port - and an useless firewire; AX8 third eye that is the same as the above and adds GURU clock first generation - the one that you install in a 5.25 inch bay; AX8 2.0 -everything that comes with the previous model but with a different VRM!

The one you want is version 2.0 because it is the only one that supports dual cores Athlon 64 X2. It should be printed in full view on the board so you should not have a problem identifying it! I got both 1.0 and 2.0 and dual cores work only on 2.0. They also have different BIOS versions and if you flash the wrong one you got yourself a bricked board.

AX8 1.0 you can see the sticker below the blue northbridge heatsink:

AX8 2.0:

I'm not planning to buy it, but it's AX8 2.0. It's visible on the sticker below chipset heatsink. Also when it boots, it displays ABIT logo with logos of 3 CPUs, Athlon 64X2 is one of them. Comes with uGuru utility. I looked at manual and it seems to be a decent model with VIA except for the SATA bug.

S939 : I used 4x2GB ECC and it did run 1T CR at DDR500 speed (some benchmarks were done).
AM2 : You can use 2x 4GB config if you want (since there are 4GB AMD sticks to buy), but they probably won't do 1066 speed though.

I have a few of those 2GB registered DDR400 ECC sticks, too much binning is needed to get 4 of them working at DDR500 (need to buy 4-8x more sticks than needed). You also don't need 8GB RAM in Windows XP and s939 is too slow for Windows Vista. For most people, the cheapest solution with good performance is to stick to 2GB RAM with s939.

agent_x007 wrote on Yesterday, 09:02:

S939 : I used 4x2GB ECC and it did run 1T CR at DDR500 speed (some benchmarks were done).
AM2 : You can use 2x 4GB config if you want (since there are 4GB AMD sticks to buy), but they probably won't do 1066 speed though.

Congrats, that must be really difficult to run at DDR-400 yet alone at DDR-500!

AX8 has some serious motherboard layout issues!
The first is the location of the main ATX & P4 connectors which are between the I/O ports and the CPU socket - bye, bye cable management! Also notice the fan header glued to the main ATX connector - a difficult position to reach!

The second faux pas is the CPU fan header which is right next to a capacitor so you can not use 4 pin connectors like the one found on Arctic freezer 7 pro! You must connect the fan to the header right next to the main ATX connector!Good luck trying that with the board installed inside the case!

AX8 has the infamous VIA VT8237 southbridge that does not work with any SATA drive except the first generation! Also it does not support SATA optical drives! An advantage of most Abit boards is the debug postcode display which is very useful when testing 20+ years old boards! A plus is also the colored front panel header.

The board has a second controller, also from VIA, VT6421 which support 2 SATA connectors and 1 IDE connector. This one has the same problem: only SATA 150 and no SATA optical drive!

And the most annoying and worst - there are capacitors right next to the PCI-express slot that are slightly taller than the PCI-express X16 connector by 2 mm and also there is a bank of capacitors below the DIMM slots that prevent the installation of any graphic card with a big and bulky cooler like GTX 285 for example!!!

So no GTX 285 for the tests, I must find a different card. I tried installing my GTX 560TI - the newest card I got - and it's a no go: the heatpipes on the card are blocked by several capacitors!
Back to the drawing board..

The BIOS is extremely similar to the one found on AV8! It uses the first generation guru chip that, while inferior to the one found on AN8 ultra, is still miles better than most BIOS-es found on other socket 939 boards.
It over-volts the memory to 2.7V by default so I manually selected 2.6V:

The board monitors 11 different voltage points and all 4 fans, however only 2 can be set according to different temperatures and voltages:

Just like AN8 ultra we also got the black box showing usage statistics: