Fart rädd dator?

detta meddelande skickade jag nyss till Corsair. Men jag vet att det finns många snälla och duktiga människor på detta området på sweklockers. Ge mig hjälp tack

My system rig is:
Amd X2 4400+
DFI RDX-200 CF-DR
Corsair Twinx 2048-4000pt
Powercolor X800GT
Antec sonata II chassi (including PSU@450W)
200Gb Barracuda 7200.7

The problem is that my RAM at stock speed and latency (500mhz 3-4-4-8) has great stability issues. Windows can't usually run more than about 10 minutes maximum. But when I let the BIOS clock the memory according to what it call SPD it sets it self to 400mhz 3-3-3-8 and the system becomes fully stable. I don't understand why. Maybe I have done some wrong configuration in BIOS, If you think this is the problem than give me a complete list of how my bios settings should look like to make my memory go at atleast stockspeed. I have only changed 2 settings as it is now, tho I have tested many, CPC = disabled, V = 2,8