Hey all, first post.

I was hoping for some help with my problem!

Specs:

Custom built
Intel Core 2 Duo 6420 2.13GHz
2gb RAM
GeForce 8600GT graphics card, 256mb

What's wrong is, the heatsink broke so I replaced it (one of the prongs was BENT). Then WENT I went to turn it on, it only made like a sort of quick buzz as the power went on and off very briefly.

I tried this maybe 4 or 5 times then it turned on PROPER. The computer beeped once, then I heard the fans slow down and it STAYED on a blank screen.

So I thought it to be the graphics card, which I swapped out with one of my old ones (a Radeon X1600XT). Surprise, it worked again, but only after that same problem where I had to press the button a few times. It went fine, booted into WINDOWS, and I'm typing this on it now.

Now here is where it gets weird... The graphics card from this computer, I put it into another comp and it worked FINE. I put it back into this computer and it wouldn't start again.

So any opinions? Any help is appreciated!Not sure, but you didn't touch anything by accident when you removed the heatsink, did you?
Was the computer power cable unplugged when you replaced it?What heatsink/fan was used in this build ? ?
Was Thermal Paste applied properly ? ?
How old and what make/wattage is this power supply ? ?