I've seen various threads about this but haven't been able to nail anything down. My PC is aging a bit and after much research I figured I could upgrade and get by at least another year with just upgrading my PSU and GPU, allowing me to play newer games such as Unreal3 and Savage2. My current PC plays WoW fine at lower settings. I got a new PSU which has worked fine for several days, and WoW worked fine, and last night once my GPU arrived I installed and everything seemed fine until I entered WoW, or Savage2. Within seconds the PC shut down. My PC http://www.shopping.com/xPF-Hewlett...with-Intel-Pentium-4-Processor-3-0E-GHz-a450n P4 3gig , it's an HP a450n. 1 gig Ram Soundblaster Audigy A few days ago I installed this PSU, ULTRA Lifesyles 500w PSU. http://www.ultraproducts.com/product_details.php?cPath=103&pPath=653&productID=659 And everything seemed to work fine, aside from cables being a bit short , and WoW ran fine. Yesterday I installed this GPU, HIS ATI x1650pro AGP http://www.hisdigital.com/html/product_ov.php?id=272&view=yes When trying to play a game even WoW, the PSU shut down, and I had to unplug the PSU to reset and reboot. I realized I installed the Catalyst drivers over the NVIDIA ones, so I uninstalled everything, ATI and NVIDIA, and then re-installed the ATI drivers and software. -I updated the ATI Catalyst drivers, -I played with SmartGart, it had turned all the options on, I turned off everything except for the AGP read/write. -I tried re-arranging the PSU cables, 1)The Floppy(because there is only 1 floppy connection and the GPU needs it) and the CDR(because of cables to short) are disconnected. 2) Left my DVD-RW plugged in on a set of cables with the Harddrive. 3) The only thing on 1 set of wires is the GPU which is using the Floppy attachment. -I checked all the cable connections and everything is seated properly. -All the Fans are working, the PC Case, the PSU, the GPU and the CPU fans. -The GPU is warm/hot to the touch but it's not scalding when it crashes, I'd expect it to get warm but unsure how warm. After all this, the PC still shuts down shortly after entering one of these games. Any insights? Is there anything else to try besides guessing between my GPU and PSU? I have as of yet tried updating my PC's BIOS or AGP, what are the chances these would make such a drastic difference in the PSU shutting off? My excitement of a newly upgraded PC is quickly turning into a headache and frustration. Looking for more ideas to try. There is a jumper on the GPU, would that lead anywhere?