When I install a new power supply in my computer, it turns on (fans spin, lights, etc.) but then turns off after 1-2 seconds. At first I figured it was due to the new power supply being faulty, but I've tried three of them now and I always have the same issue. I've tried with two Corsair TX650s and one TX550M. I don't think it's a problem with how I'm connecting things since I can put the stock PSU back in and have everything work.
How are you turning it on & off?
I ask because I've run into where theres an on/off switch on the back that it will turn on briefly and then turn right off but they've all worked fine when I leave the rear switch on and then press the power button on the front of the pc.