Computers crashing! Urgent help!

Hi!

I bought two computers in parts about 6 months ago.
They have been working flawlessly (some trouble with graphics driver, crashing when playing 3D games, but I could live with that).

The computers consisted of these components:
MSI Sis 655
1024 MB TwinMos Winbond RAM
Sapphire Radeon 9700 Pro / non-pro
2,5 Ghz intel P4
120 gb Western Digital (?) and 80 GB Matrox
CD burners for both.
One computer had Cheiftech 350 W and the other Antec True power 430 W.

The computers had problems during games, it all began with me playing Blitzkrieg and the game froze the computer totally. I turned up the graphics volt to 1.6 on one of the computers and it worked fine.

Anyway, one of the computers suddenly crashed. When I tried to turn it on, it beeped three times (instead of one). I tried clearing the CMOS, and the computer started, but complained about low CMOS battery. The battery was fine, and a few days later, the computer stopped working at all. The screen would not be turned on. It is never in stand by mode, it just has a sign on it telling me to check my cable. But it's fine!

I exhanged all components between the computers (I'll call the non-working computer for A and the working for B).
The graphics card, memory and CPU on A worked fine on B.
And when I tried the motherboard from A on B (including HDD and energy supply), it did not work! So I sent the motherboard to the store to have them look at it (still havn't heard anything).

Now, my other computer started freezing. It could freeze at any time, even when just surfing. It always froze again, when you just came into win XP, after rebooting it from the first failure. So it crashes two times in a row.
I could live with this, but now it acts just like the other computer. The screen does not go on! I tried taking out 512 MB of RAM, and swapping it in different slots. I got the computer working for one day. Now it's not working again, and swapping slots does nothing.

PLEASE HELP!! Sorry if this is long!
PS / I have several fans, and the CPU and system only shows 35 degrees Celsius. I have F-secure with updated virus definitions and it shows that I have no viruses..

had an msi 648 (sis) with same problems you described. Eventually, tech at retailer determined it was a bad mobo (memory processor). RMA'd it, new board been ok ever since.

Hi!

First, how do I reset my bios?
If it is a memory resident virus, can I get rid of it?

OK, i disconnected the HDD and took out all the RAM, but still nothing happens "no signal input"