Corsair PSU

I hate posting non-DS related stuff here but I always get the best advice in this forum so here goes. I decided to upgrade my GPU and PSU. I initially bought a corsair gs800 and an nvidia gtx 560 ti. I'm very happy with the GPU but I noticed a buzzing noise when the PSU fan turned on. Once the fan was on it was very quiet but a buzz noise would happen just before the fan on the PSU turned on. At any rate I exchanged the PSU for a Corsair AX750M.

Now it gets interesting. I assembled everything and really liked the modular PSU. I turned the computer on and within 15 minutes I was on a web page and the monitor went black and then came back on (few seconds). So that was weird. I have real temp checked my temps and everything was good. Then I started a game *whispers* World of Warcraft...10 minutes into the game and computer restarted. Then 15 seconds into startup it restarted again, then again, then again. Finally, I shut the switch on the PSU to off for few minutes. I felt the PsU and it didn't feel hot. I turned the switch back on and tried powering up the computer and nothing happened.

So now I'm thinking the PSU is fried. I open the computer and take out the PSU without unplugging anything and as a last try started the computer. It started fine and ran fine. I ran a stress test and no problems. I put the PSU back in the case and haven't had a problem.

Any ideas on why this happened? The only think I can think of is maybe a wire was touching something it shouldn't have.