I've been having trouble getting my memory to run at full speed on this new to me motherboard. It should run at DDR400 speeds. If I run one stick of 512MB memory in slot 1 I can get the stuff to run at top speed. If I populate slots 1 & 2 or slots 1 & 3 then the most I can get out of the memory is less than DDR333 speeds. This is the case with three different types of memory, two of which are from ASUS's recommended list. The third is some high end memory that does run at DDR400 speeds on the mobo it was originally purchased for.
I originally tried to downgrade my BIOS by flashing it with ASUS's ASUSUpdate Windows tool, but it wouldn't let me flash an older BIOS over a newer one. Tonight I finally reinstalled a floppy drive so I could downgrade my BIOS to an older version that allowed for changing memory timings.
1) I downloaded the 1005 BIOS zip file from ASUS last week.
2) Today I unzipped it and then renamed it to K8VSEDX.ROM
3) Then downloaded AFUDOS.ZIP from the ASUS site.
4) Unzipped AFUDOS.EXE from the ZIP file.
5) Copied both AFUDOS.EXE and K8VSEDX.ROM onto a floppy that had been formatted as a boot disk.
6) Rebooted and in BIOS I enabled the floppy drive.
7) Rebooted and then set up my BOOT order. (Wouldn't let me set to boot to floppy until I did this)
8) Rebooted and came up at the A:/ prompt.
9) Typed 'afudos.exe /ik8vsedx.rom' at the prompt, hit enter and prayed.
10) The flash worked and memory timings are again available.
At the time I had Kingston memory installed so I tried to manually set the timings to 3-3-3-8 @ 200MHz. According to the memory's SPD these settings should work, but I couldn't even boot into Windows. I tried to loosen them up a bit while still leaving the speed at 200MHz, but the system wouldn't boot all the way into Windows. I reduced the speed to 150MHz and set the timings to 2.5-3-3-7 and the memory worked stable. One note, I used the same timings with the speed set to 166MHz, but CPU-z still reported the memory running at 150MHz. Not sure why.
I replaced the Kingston memory with Kingmax and manually set the timings to 2.5-3-3 per their spec sheet. Windows booted up and everything seemed to work. HalfLife 2 looked and played right. Dungeon Siege however showed artifacts. Per the memory's reported SPD settings I loosened the timings to 2.5-4-4 at 200MHz and then even Dungeon Siege looked right.
Both the Kingston and Kingmax memory are from ASUS's recommended memory list, KVR400X64C3A/512 and MPXC22D-38KT3R respectively. Both types are 512MB sticks and I have two sticks of each. Neither setup at whatever speed settings reports as working in dual channel mode even with two slots populated. Again, not sure why. More memory stability testing is in order, but for now at least my memory is running at top speed possible.
Update: Well I've been corresponding with someone and together we've been comparing results as far as getting memory to work at full speed. I shared the above info with him. As far as the memory running in single channel mode, that is normal. There are some differences between the 754-pin and 939-pin Athlon64s. One of those differences being that the 754-pin chip only has a single memory controller while the 939-pin chip has a dual controller. Thanks Joe.