check out this thread http://www.tomshardware.com/forum/302560-30-computer-reboots-turning
, if reconnecting everything and making sure they are in the right place then t looks like the BIOS is trying to re-set itself because it thinks it's unstable. Also, you OCed via the BIOS right? Also, did you install the EPU software that came with the driver DVD? ,Could be your mobo deciding it doesn't like the OC and trying to reset ,could be that your GPU and your OC are abit too much for the PSU , it might not be able to give enough amps from a cold boot. Thats why it starts, resets, warms up and then starts again with enough power to run fine.