Hi i just installed an EVGA SR-2 1200w power supply into my comp the first time i booted it up worked fine but then went back and connected my hardrive it would constantly turn on and off even though mobo lights were on.
Specs* Asus P7P55D-E-DELUXE mobo 640gb western digital GTX 460 1gb sli Intel Core I5 750
More aboutboots turns
weird...recheck your connections
That suggests a short somewhere. See if the problem only occurs when that particular hard drive is connected. Make sure you didn't plug an 8-pin PCIE power cable into the CPU power connector.