I'm not normally one to have to ask for any assistance with these kinds of things, but this one really has me going. The scenario I'm having is that I built a new Pentium D 820 based system with a GeForce 7800GT PCIe card and 1GB of ram recently and am having some issues with stability. More precisely, when I put the system under very heavy load (the most extreme being running into Ironforge during peak times while playing World of Warcraft and sometimes having a Skype conference also going. This often involves lots of drive thrashing as it quickly tries to load massive amounts of textures from the HD to the graphics card) my screen will occasionally black out for 0.5 to 1 second, then come back. Most of the time it will do that three or four times over about 5 minutes, then eventually it will flicker black, then immediately proceed to a bluescreen. (IRQL_NOT_LESS_OR_EQUAL_TO most of the time) Now, to make it even more interesting, CPU load doesn't seem to have too much of an effect on it, as I have run Prime95 (two copies simultaneously to max both cores) for about 12 solid hours with no errors at all. Memtest has run for many hours as well, without errors. My system specifications are as follows: Pentium D 820 Intel Desktop Board D945PSN 2x 512 MB DDR2-533 1x 200GB Seagate HD GeForce 7800GT 256MB Graphics Antec 500w Neo HE PSU Sound Blaster Audigy Now, here is what I have done so far... I've tested the memory thoroughly, replaced the two 512MB sticks with new ones, and tested them again in both single and dual channel modes with various timings just in case. (memtest86+) Run a couple HD diags like Hitachi's DFT and Ontrack's little tool to check that. Tested the power supply for issues with a couple different ATX PSU testers and a multimeter. Checked for overheating issues on the CPU, northbridge, and graphics card. (all are falling well within acceptable temperature ranges) Tried turning off many of the miscellaneous peripherals that are built onto the motherboard (sound, parallel port, etc.) and have removed ALL non-necessary pci cards from the system while testing. I'm going to zip and attach a set of several minidumps, as they're itty bitty and may share some insight I'm missing when I looked them over with the Windows debugging tools. Thanks in advance for any help you can provide!