Why does my computer turn on then cut out then boot fine??

[pinkpotato]

Well its been doing it ever since i clocked my i7 930 up to 4.2 ghz and never did it @4.00, and it only happens if the computer have been turned off at the wall socket. My oc is stable to 40 runs of linX and 6hours prime. I just wondered what it was, does my mobo and cpu not get enough power straight away or sommething and its cuts out like a safety feature?

 

[pinkpotato]

Thanks for all the replies, ive got an antec cp850 psu and i have a power meter on it and the highest its recorded is 590w so thats fine. So i guess its either the capacitors charging or the mobo, been running like it for 6 months but never worried much as its always operated fine