Hi,
I have a Biostar Tseries TA790GX 128M board and AMD Phenom X4 9650 CPU.
Everything has been FINE up until I REMOVED and re installed my CPU. There's another board I wanted to test, but had no CPU handy. So I USED this (my) CPU to test it. Now that I installed it back, the computer didn't go any further then preBIOS screen, no beep, nothing, just that screen with Biostar logo. Decided that I've screwed the CPU. Uninstalled again and installed on that other board. Everything is cool. So CPU is OK. Tryed installing it along with putting some pressure on it (pushing down). After a couple of attempts video SIGNAL was GONE too, no video at all. Later on after more attempts video came back, but still that screen. So my guess is one/some of the pins on the socket is broken or displaced I don't know. Is there a way how to dismantle the socket itself to see what's going on underneath?
Your help is appreciated.

Kind regards
 Thanks all.
I just resolved it. Believe or not after uninstalling, re installing MoBo it started normally. My guess though is it had nothing to do with re installment, this time I was just lucky. Restarted, stop-started multiple times. It's still OK. I know that it may reoccur in the future if I remove CPU again. Will try to not remove it.

Kind regards