Hey guys. It's not an old computer or anything. AMD Athlon X2 processor, NVidia Geforce 7900 GTX graphics card, 360GB SATA HDD, 2GB RAM, the works.

The problem is, that a couple days back one of the fans died on me. I kept it off for until I could get a new fan, which was no big deal. Plugged it in, powered it back up, etc. However, when it powered back up, it would receive power for a brief second (if that), then just completely turn back off. All the fans would start spinning, the lights turned on, and everything, but it turns off almost as soon as it turns on.

Could be a short in the motherboard or PSU, either from installing the new fan or whatever burned it out (probably not the latter if you were able to shut-down after it went out). Make sure you hooked up the new fan properly, and if possible try a different PSU (or get this one tested).

I'd also try taking out the new fan, just in case. As long as it wasn't the CPU fan turning the system on missing a fan wouldn't hurt anything. A computer can run in a normal climate can run fine without any case fans indefinately if the side panel is open (things will get a little warmer than you want, but it shouldn't over heat unless you're under very heavy load), or for a few minutes with the side panel closed. So don't worry about turning it on to test it.

Sounds to me that the system checkes if all the fans are present and connected. I had a similar problem with a notebook and found out one of the fans wasn't connected right. Does the system power up when you reinstall the damaged fan?