My problem:
Certain games seem to run for a couple minutes (3-5) and then crash the system, UT 2004 in particular, but also FEAR Combat (only tried to run it once). (...and yes..I have the Epox EP-9npa+Ultra, so this isn't the wrong forum.) I currently have 4 x 512 MB of Corsair Value RAM (PC 3200). However, previously, I only had two sticks for 1 GB. Before adding the other two sticks, UT 2004 ran fine, if I remember correctly, which suggests that the new RAM is bad. However, I ran MemTest86 on it for three hours (4.5 passes) and it didn't reveal any errors.
Could this be an issue related to how the motherboard deals with 4 x 512 sticks of RAM or could it be an issue with the nVidia NForce4 motherboard drivers? I haven't updated my drivers since I built the computer in February and flashed the bios to 9npa6103 (released in December 2005, I think). Could this be a BIOS or driver issue, or should I continue to suspect the RAM as the culprit?
Video card is a Connect3d x800 GTO unlocked to 16 pipes running at stock speed (no need to overclock it yet). I don't suspect it as the culprit since UT 2004 seemed to run fine on it in the past and I've run UT '99 without a problem (not that that would stress the card much).
CPU is an Opteron 148 (stock 2.2 Ghz) overclocked 25% to 2.75 Ghz. Might it be possible that the overclock isn't completely stable?
The RAM was purchased at two different times in two 2 x 512 pairs. I'm pretty certain that I would have installed the first two into the proper slots for dual channel. Is it possible that the two different RAM orders, although the exact same model, aren't completely compatable? If you had 4 sticks instead of 2, would you want to put the matching sticks in different RAM banks than the banks you would put two sticks in for dual channel if you only had two sticks? (Just putting it out there, seems far-fetched.)