Hi All, I tried posting this on the NVIDIA forums, but didn't get much of a response. I just bought an HP m8407c (it was cheap), then bought a couple small upgrades. First off, the system is an Intel Quad Q6600 w/ Vista 64. It came w/ a single Asus GeForce 8500 GT (it's not SLI) and I got a PNY 8600 GTS 256mb to put in instead.. not a big deal. At the same time, I upgraded the PSU to a 500w OCZ StealthXStream (two 12v rails at 18a per), and put in a couple new nVidia DIMMs that came w/ the 8600GTS (i figured they'd be better than the memory in the PC.) Booted up and everything's fine... Installed the drivers for the 8600, ran some windows update junk, etc. Then, it started happening -- seemingly at random -- that video would go black, the fan kicks up (loud) and the monitor loses signal. I have to power off. It will ALWAYS occur when: - I try the Windows system rating thing -- and I assume when it's probing the video - When I preview a screen saver (the one w/ bubbles or something). I believe it uses Direct3D However, it also happens sometimes when I go into config screens (no pattern) and then I tried Ubuntu64 and got the same thing 2-3 times in there. I've tried about three different NVIDIA drivers in Vista with no improvement. Note, I haven't done any gaming on here. Every time I've checked the temp, it's been between 48-52 degrees C. So.. now what? Should I just try to return/exchange it? Or is it likely some sort of incompatibility w/ other hardware? I did NOT have anything like this happen w/ the 8500 GT.