Hi there, I recently decided to upgrade my video card(from nVidia 8800 to Radeon 6950). The card was a bit large so I had to unplug and replug some cables in order to get it in, and after that the computer would not boot. It received power, the fans ran etc, but the monitor got no signal and the keyboard didn't light up, so I am assuming it is a false boot. After switching stuff around and trying different PCIE ports, I gave up and decided to try to get it back to a functional state. So I put in the old graphics card and made sure all of the cables were back in their original spots(I had moved some SATA cords to different slots to make room), and... same problem. Computer receives power, but no boot. I have tried reseating the RAM in case I loosened one of the sticks. Although I don't recall what the configuration was when it happened, I did somehow manage to set it up in such a way that the new video card's fan was blasting like a jet engine, which may or may not be relevant. I have looked all over the place but most threads on this problem involve either a dead video card(not the case, the original isn't working either) or a dead PSU(also was working fine before I switched, and it is also brand new). Notably, not long ago my old PSU wore out and exploded. It was an OCZ PSU and after replacing the PSU the computer worked fine. I suppose it's possible it did some damage to the mobo that didn't turn up until I tried to switch cards, but I'd like to exhaust my other options before I go looking for a new motherboard. Thanks for any help. Edit: I forgot to mention, often when I kill the power to the machine and let the power bleed out, and then try to turn it on again(no response from monitor or keyboard), it will start run for a brief time, then restart itself. The fans and everything shut down momentarily then turn back on. It then runs indefinitely, and if I turn the computer off without killing power it will always run indefinitely until I turn it back off. Only killing the power supply makes the restart cycle occur.