Built new PC but screen randomly turns off

Question

I built a new PC yesterday, with the following specs:

• Intel i5 2500k
• 8GB DDR3 RAM
• Gainward GTX570 Phantom
• MSI P67A-GD80 (B3) Motherboard
• OCZ Agility 3 SSD

The build went fine, and the PC has booted properly and windows was installed fine on the SSD. I also read a few guides which recommended overclocking the i5 so I put it up to 4Ghz with 1.25V VCORE and it ran stable for 30mins of prime95 with temps of 45C. An initial memory test on the BIOS also seemed fine. GPU temps were very good at around 33 idle (not sure about load though).

Left it running overnight to download something. When i checked it in the morning i found that the PC was still on, all fans running, etc; but the screen was on standby and mouse and keyboard (USB) were not lit up. It would not work no matter what i pressed.

I hard reset it and went back into windows. Everything seemed fine, so i shut down to go to work. It came up with one of those "updates installing don't shut down etc" messages, and the screen turned off shortly after, in the same way as observed earlier.

I am going back home from work now, and I wanted reccomendations on what to try. My ideas so far:

• Overclock is bad, or CPU is undervolted. Set to factory settings. See what happens.
• PSU is too weak (650W). No idea how to test.
• GFX card is not getting enough power (fairly sure cabling on that is correct, + they usually whine at you if they are badly connected)
• Faulty component. I hope not

I would appreciate any help.

Answer 1

Your first idea is definitely what you need to do. You cannot just OC your machine with the same settings of a similar machine, OC'ing doesn't work like that. Even machines with the exact same parts often require different settings when they are dialed in. Always start with factory settings on a new build, and install the OS with the factory settings in place. Head over to Overclocking.net where there is lots of good info on how to properly overclock a computer. Guessing at settings usually doesn't work unless you really know what you are doing and get lucky.