My issue today is preceded by a strange little story. A few months ago, in an attempt to speed up my graphics, I bought a 650W power supply. The one I was using before was at the very minimum power for my video card to run. So, anyway. I install it, boot up, everything seems to be fine, computer is running well and the graphics are much smoother. A few days later our power goes out, and when I tried to restart the computer, the fans turned on, but the HDD didn't seem to power up, and my CD-ROMs would not respond. The light on the power switch was on, signifying that power was there, but it was dim. The HDD access light did not even give a flicker. So, thinking the power outage somehow fried my power supply, I took my old one and put it back in. Booted up, everything was fine. A while later I decided to see if my power supply really was fried, and installed it back and powered it on. Everything was fine. Until I rebooted. Then I got the same issue. Turns out when I have that issue, all I had to do was boot the computer under the old supply then reinstall the new one, and it ran fine until reboot. Strange, but it worked. I very rarely turn off my computer, so I figured this would be fine and just went on my merry way. Last night, my pc was on, and when I went to hop on it, the screen was blank, and the only thing I heard running was the fans. I thought it was strange because the computer had not been powered down. But I did my usual workaround but this time it didn't take. When I install the old power supply, the same thing happens. Neither supply will work, and I've got a big paperweight that blows some air through it. Anyone have any idea what could be causing the problem and a possible way to fix it? I've never seen such a thing...

It sounds like there may be a problem with the PSU connector itself. Possibly on the MBoard. Try reseating the PSU that is currently installed and see if that makes a difference.

I agree with Othehill, the power connector was my first thought. But it could also be a flaky connection elsewhere on the motherboard. The flexing of the board caused by the unplugging and plugging of the power supply connector might be causing it to make and break.

I took your advice and was messing with the IDE cables, power connectors, and the connections between the switch and mobo. I got the lights to come on full intensity. didn't get a signal to my monitor but that may be another issue altogether. But apparently I re-loosened whatever it was that I tightened. I'm going to mess around with it some more and see if I can reseat whatever it was I wiggled loose. At this time I'm not sure if it was going into full boot or not. I'll let you know. Let me know if there's any other ideas that come to mind.

So here's my update. It turns out the power connectors are fine going from the PSU. However the SCSI cables going from the mobo to the HDD and the CD roms seemed to have died. Don't know how they both died at the same time....but anyway, when I remove them completely and turn on the pc, I can hear the HDD spin up and I can open the CD roms. However even after replacing the HDD cable, there is still no image on my monitor. Still says "No Signal." I hope my video card didn't get fried too.