Shutdown behaviour without possibility to start again

Sinus

Honorable
Dec 5, 2013
1
0
10,510
Hi,
My newly built computer worked for a month. Then, starting a re-installation of Windows from CD, the computer suddenly shut down during the copy files phase. It was not possible to start it again, so I unplugged hard drives one at a time. After each HW change, it was possible to start the computer once more, but the same shutdown occured once the computer started doing some "work". At last I had only one hard drive and the cd drive. Same behavoir. Unplugging the hard drive, it seems to work to run Windows from disk (I haven't tried this a lot though).

I'm suspecting something wrong with the motherboard or power supply, but I really have no clue what it can be. Can anyone please help. Thanks a lot!

Power Supply: Seasonic X-650 80 plus GO
http://www.seasonicusa.com/NEW_X-series_KM3_650-750-850.htm
Motherboard: Z77 Extreme4-M
http://www.asrock.com/mb/overview.asp?Model=Z77%20Extreme4-M&cat=Specifications