Basically what happened was that one night my computer turned off and would not turn back on. Reset the power cord just gave a brief second of power before not doing anything until the power cord was reset again. I tested my PSU (Corsair HX620) with the paper clip trick and it did turn on (had it run my fan and hooked up my HDD to another computer with it). I thought it might be a blown PSU as with some of the posts in my other thread hinting at that as well I picked up another PSU (Corsair GS700).
When I plugged up my new PSU, the computer got power. The fans turned on, my LEDs turned on and everything seemed to be on...but my motherboard showed code 00 and would not boot. Just on a whim, I hooked my old PSU back up and it did the same thing as my new PSU. I am currently finishing the RMA for my motherboard and what I'm wondering is this :
Do I hook my old PSU back up(it started running the computer just like the new one when I hooked it back up last) or do I stay with the new one.
So I'm wondering...is it safe to hook the old PSU back and use it in my computer...or should I switch? I figured if the PSU was blown or caused damage it would not have turned the computer on at all later on.
If the PS boots the computer and has consistent voltages with no spikes, you should be good to go with the old one. Before relying on it, I'd check with a Power Supply Tester to see if the tester throws any errors. After that I'd check the BIOS in the new MOBO to see if you get any wandering voltages. If you don't see anything funny, I'd use the old one and keep the spare, unless you need the greater wattage on the PSU, then I'd just keep the old one as a spare.
Since you get the same symptoms from both power supplies then the problem is most likely with the motherboard's power VRM circuit for the CPU.
The fact that the fans and LEDs turned on indicates that the part of the motherboard that is powered by the 20+4-pin main ATX power connector is working.
The CPU's power VRM circuit is not on the same circuit powered by the 20+4-pin main ATX power connector. It uses the 8-pin or 4-pin EPS12V connector. If you forget to plug in the EPS12V connector you will get the same symptoms you've described. A failure in this power VRM circuit will also exhibit the same symptoms.