Originally Posted by Thelis
You also might have fried it seeing as how you didn't put thermal paste on.
I've taken out a processor and put it back in on another mobo with the same thermal paste (the processor was removed from the heatsink) and I had no heat problems and used it for quite awhile before I got a P4 replacement for it, now I need new thermal paste and heatsink so it won't overheat with a stock heatsink. It was a Celeron, do they get hot at all?
As for damaging the processor... You could have bent a pin or pins which makes the processor go in the slot in correctly or not at all. When I bought My P4 (used) I put it in the slot and threw the heatsink on (just for a quick test) and no post. We came to find out that a few pins were bent and it wasn't seating properly into the socket, and therefore not posting... Once the pins were bent back in place it fit in the socket and the mobo posted.
You could have killed your RAM, which leads to no mobo post. You could have also killed your video card, which leads to no picture on the monitor...
If you didn't know what you were getting into on the inside of your PC, why do all that stuff?