Here is a good one I'm not realy new to this sport. But I have never come up with this kind of problem before. Just built a new system. spec are not that important for this problem. Asrock X533 P4 2.4Ghz 512 pc 2100 500w power supply System went together with no problem. Burned in with no problem about a week ago shut the system down and went to bed, got up the next morning and nothing , every thing spunn up but no post. Ok so i say to my self, Self you never should have got a chepo psu sooo It's time to buy a new quality one, untill then I STEAL my wife's psu 250w but the system runs ok alittle short on power but if i just run what i need to get buy it'll work. I wanted to test this psu so I stick it in my wife's system and lo and behold it works great, WOW that's strange but I want to test it even further so I take it and put it on another system, I have no problem works great. So I go and get a 600w psu and try that in my system no post as before Hmmmm Coud be a bad psu ? Try it in my wife's and whamo works great. stick the 250 psu back in my system and it comes up just fine. So my queston is has anybody ever herd of a problem like this?