Alright you techies, I need some help.
In my box, I have an AMD +4400 and 2 7900GT's. When I have SLI enabled, I score approx 8000 on 3dmark06, get approx. 65fps in GR:AW and 150fps in the CSS video stress test with everything maxed out.
When I disable SLI, I get a much lower 3dmark06 score, approx 45fps in GR:AW BUT 175fps in the CSS video stress test with everything maxed out.
I gave you the details to rule out "SLI is not operating properly." The 3dmark06 and GR:AW benchmarks prove that it is. I've heard some rumors around that the HL engine doesn't work well (optimize) duel cards. Has anybody else ever experienced this or come across something similar?
Solutions I've tried: Reinstalling CS:S, and new beta drivers (9.28 and 8.43 tested).