PC SPECS:

Windows XP Pro SP2
Core 2 Duo e6400 2.13GHZ
Gigabyte 965P-S3 Rev 1.0 F13i bios
256MB Albatron Geforce 7950GT
2GB Corsair XMS2 DDRII 800MHZ (2x1GB)
Antec NeoPower 650w
19" Samsung 940B

CPU and Graphic Card have a custom fan so temperatures are good.

On bootup, computer starts, but then turns off, and starts again, making a one long beep and two short beeps. The computer just hangs, not booting to bios, and the monitor stays blank.

I looked in the manual and it said one long followed by two short beeps is a graphic card or monitor error. Tried re-seating the graphic card, no effect.

I hooked the monitor up to a friends laptop and it worked fine.

Tried resetting CMOS several times, no effect.

I kept unplugging and plugging cords back, and graphic card/ram slots in and eventually it booted up slowly into Windows.

However the computer is extremely sluggish and slow now. OS and applications take a long time to load, Mouse and menu movements are very sluggish.

Tried a different RAM and Powersupply, still the same problem.

This leads me to either a MOBO or CPU problem. Graphic card.. there are no artifacts or anything on screen.. and I don't have the resources to test with a different graphic card.

Any help or tips would be greatly appreciated.

I would say the first thing to try is swapping out the graphics card.