Hello everyone and thanks for stopping by my question. I have an AMD 3200 which I just upgraded with an ATI X1950 Pro 512mb. So I also purchased a Mushkin 550200 550W power supply off newegg to power the hungry vid card. It worked flawlessly... for about 1 month. Then, while on vacation, my bios battery ran out on my board and I replaced it when I returned. I reset everythig and ever since then, when I drop into a 3D app the pc beeps and goes black like it's rebooting but it just hangs there at a black screen until I totally power it down and wait a few seconds before turning it back on... and then it's fine til I try a 3D app again. I'm runnin a Gigabyte 7NNXP mobo with a gig of ram. I'm personally leaning towards the power supply... it's dual rail and I'm thinking it's crapping out when it draws on them. Any thoughts would be greatly appreciated!!! Thanks!!! I've pretty much tried everyone's suggestions, but to no avail unfortunately. I placed a support request with Mushkin and we'll see what they have to say. I am getting some really strange voltage readings on my Mobo Monitor so maybe it really is a bad PSU. Thanks for all the help anyways!!!