Before we go forward and run some of the tests that we are going to see hereinafter, let us check a few of the symptoms to understand if those tests are worth doing. We have mentioned some symptoms ...

1] Does the PSU fan spin on startup? Some users reported that their Power Supply Unit fan spins on startup but stops after some time. Others reported that the PSU fan does not spin even on startup.

Upgrading from a 4870 to GTX 570... BFG LS 550 Continuous PSU. 4 12v rails 16amps each. I7 920@3.8Ghz, 1.25 vcore. And given that these back of the envelope calculations are probably conservative, and ...

that's an at power supply. i'll let the c&cf guys explain the rest (since this thread will be there in about a minute).