One morning I turned off my computer to restart it. Then it shut down normally. I press the power button and nothing happens. No lights or fan noises or anything.
I figured it was my PSU because I can hear this weird high pitched electrical interference noise when I flip the switch on the PSU.
So I pull out the PSU, use a paper clip to connect the power line and a ground line on the mobo connector. The PSU still works. The fan spins and everything. When I connect it back to my comp, it still wont turn on. It seems the fan is really weak when it spins (maybe bceause its not powering a system and there no load on the PSU? idk?)
So what do you guys think it is? Should I blow $130 on a new PSU? or should I blow $600 on a new i7 system. ($600 dollars I dont have.)
The following is a cut 'n paste from a previous post: Try to verify (as well as you can) that the PSU works. If you have a multimeter, you can do a rough checkout of a PSU using the "paper clip trick". You plug the bare PSU into the wall. Insert a paper clip into the green wire pin and one of the black wire pins beside it. That's how the case power switch works. It applies a ground to the green wire. Turn on the PSU and the fan should spin up. If it doesn't, the PSU is dead.
If you have a multimeter, you can check all the outputs. Yellow wires should be 12 volts, red 5 volts, orange 3.3 volts, blue wire -12 volts, purple wire is the 5 volt standby.
The gray wire is really important. It sends a control signal called something like "PowerOK" from the PSU to the motherboard. It should go from 0 volts to about 5 volts within a half second of pressing the case power switch. If you do not have this signal, your computer will not boot. The tolerances should be +/- 5%. If not, the PSU is bad.
Unfortunately (yes, there's a "gotcha"), passing all the above does not mean that the PSU is good. It's not being tested under any kind of load.
Having said all of that, from what you have written so far, you could have a bad PSU. That's why you need to do more troubleshooting.