Well, more trial and tribulations on my new build (really no time to put it in production, so still on the bench testing).
Again, here's the config:
E2160
Asus P5K-VM
2x1GiB OCZ Platinum Rev2 DDR2-800 (speced 4-4-4-15 @2.1V)
Antec NeoHE 430
Everything tested fine with the IGP, even at 333x9 with the RAM running at DDR2-800 (using the ratios of course).
Borrowed a friend's old BFG 6800GT OC, and it has never been stable for too long. Since I tested the other components for weeks with no trouble, I thought just plugging in the video card with such an ample PSU would be enough (still not breaking 200W draw at the wall, according to my Kill-A-Watt). Long story short, there is an overheating problem which I seem to have resolved with a ghetto-mounted fan blowing the back of the card and the NB heatsink (stupid new ForceWare forced the fan to spin at 53% always I turn it back up to 100% with RivaTuner ). Between BSODs, random hangs/shutdown, and OS reinstalls (it corrupted things that bad), I finally caved and ran memtest and sure enough it failed, which explained everything (or not?). I've backed things down to DDR2-667 and it seems to be fine after about 6 hours of memtest so far (CPU still at 333x9).
So I ask, is this possible? I did test all the other components with the IGP enabled. PCIe has always been manually locked at 100. Assuming my PSU is good (RTHDRIBL+Orthos test run that was stable showed <200W of draw), how can this be? Bad video card or the NB being iffy at handling the new x16 load while overclocked? I suppose if my board has those NB tweaking option I could try but I guess I'm stuck now.
That said, I would eventually get another card, so this means I have to retest the whole thing? Ouch.