Mine issue it the same but my PSU is ok yes after Power shut Down to bad i have also not connected my UPS with my PC what i think is that bios is corrupted and bios not even entering or i cant even enter the bios and computer is hanged this problem is on this link or the bios chip may to be replaced bec if you cant get in bios or PC hangs during post how can u even update to reinstall bios what u say
http://www.techspot.com/vb/topic28558.htmland that persons post is as follows
Within the past week, my computer kept randomly rebooting, and eventually stopped turning on at all, so I bought a new PSU, and now it boots, but only to the POST screen, I try to press F2 to load the BIOS, but it does nothing. I also tried changing the jumper to boot into the BIOS setup, but it still stuck on the POST screen, but says "setup loading" instead of "press <F2> to enter BIOS setup" I am completely lost and have swapped out and checked the PSU, RAM, GPU and CPU. I am afraid it is a motherboard or HDD problem. Anyone have any ideas? Thanks for your help!