Hi there! Thanks in advance for any help you can give to me.. My home built pc has been working perfectly for the past 2 years. Today the pc made a windows registry update and shortly after (say 5-10 mins) the pc closed down and would fire up for a split second only - afterwards. I removed the PSU and used a paper clip to test the PSU and the fan started up, i connected the PSU to my hard drive, disc drive and they both started up without shutting down. When I connected it to my motherboard the lights of the board light up, but when I power on the motherboard it starts for a split second, shuts down and then will not power on at all afterwards unless I leave it for a 30 seconds in which it repeats the same process. Could this be a bad power supply unit although it did seem to work well when powering disc and hard driveindependently. Motherboard has not been moved or bashed around, was brought brand new, Asus deluxe z77. Also to mention that the heat sink fan spins and cuts out with the rest of the equipment on powering up. There is very little dust in the heat sink fan.. I have also removed the ram and tried to boot the mother board and cpu independently with the same result.. Confused, would be a shame if motherboard was faulty as it was new, undamaged and could not see why there would be a problem from nothing happening to it. PSU is a corsair CX 430 i7 3770k processor 16gb corsair vengeance ram Velociraptor harddrive Samsung disc drive Thank you as any help and advice is appreciated !