Sli problem with screen artefacts

[lykathea]

I have problem with Sli. When it's enabled, i have artefacts in 3D apps like 3dmark03, 05 or UT2004 (also in windows when i start Sandra 2005). I have 2x6800GT and MSI k8N Diamond. I just tried to change all hardware (gr. cards, Mobo, PS, Memory, CPU, HDD), I have latest drivers, bios, nforce drivers, but nothing helps. It looks like Electromagnetic Interference or what.

 

[ChrisQuintero]

I used to have that problem all the time when my board was getting too hot.. are you overclocking?