I just got my GTX 690 Quad-SLI running and when I went to do benchmarks with Unigine Heaven, I notice that my fps result vary very widely. I know that you never get the exact same result every time but in my case when I did Heaven, I got score from 1.1k points to 3.3k points. Also, when monitoring the bench with MSI Afterburner and my UPS wattage monitor, I notice huge differences corresponding with the scores I get.
This was done without overclocking the GPU's aside from increasing the power draw to 135%.
This is my system:
ASUS P8Z77-V Premium
16GB DDR3 1600Mhz CL-9
GTX 690 Quad-SLI
Seasonic X-1250 Gold
Samsung 830 128GB
2x Samsung 830 256GB
WD Caviar Black 2TB
I've been monitoring my GPU's using MSI Afterburner and from what I've found, in most cases they are working properly at max load but on a couple of games, I'm getting performance drops in the double digits.
The issue seems to be with the drivers since I've tried 301.42, 304.79, and 306.02. I get different performance changes on each one. 306.02 seems to fix nearly all of it but at the expense of degrading performance on Battlefield 3 and Crysis 2.