Question : Problem: Computer restarts. Funky burn on bottom of MoBo

I have a problem with my computer. It restarts shortly after it has been turned on. Upon restart, the video card fan spins up to maximum speed and the system stays there with a blank screen. I went out a bought  a new video card, same thing. Also I noticed this new video card gets REALLY hot.

Since both cards did the same thing, I am left to blieve that my problem is either with the MoBo or the power supply.

What would be the most logical next step to fix my system?

The system has been running solid until now.
I reset the BIOS, Pulled the motherboard out of the case, started it with minimum devices attached. Removed one module of ram.

Has anyone ever seen this happen to a motherboard?

Images of motherboard below

Proc : Intel Core2 Duo
Motherboard : Intel DX38BT
Video card : ATI Radeon 3870x2
New Video Card : ATI Radeon 4870
Power Supply : Antec 850 watt TruePower Quattro

Answer : Problem: Computer restarts. Funky burn on bottom of MoBo

>>    Can the bios be changed from the OS level?<<< sure it can; you can even flash it
  >>  Can power strips with no surge protection cause any issues I have been seeing?   <<   power spikes and problems can cause almost anything
you may have have trouble with capacitors in mobo or PS, and after a while they loose the load, and get functional.   PS'es can go into protect by spikes
dust - normally - is not conductive, and does not harm, unless it blocks the cooling