On Then Off

[Candyy]

I have a computer that has been running fine up until a few weeks ago. It then started overheating while playing certain games. I did some research and figured it was the thermal paste that was causing the issue. I replaced that and now when I boot my computer up it runs and all the fans start and I will get one beep and occasionally a second but then it powers off. All in the span of around 7 seconds. I don't know what it could be. Help is GREATLY appreciated. Thank you

I am using a Crosshair V Formula motherboard, GTX 680, and I have watercooling with air cooling.

 

[Adam Ashworth]

Does the CPU fan definitely start? I had this happen to a friend and it turned out he's forgotten to plug the CPU fan back into the mobo after re-applying the thermal paste.

 

[Candyy]

How can I see if it's running? It is just a box with a fan controller on it with the two tubes plugged into it. The fans above the radiator?