Erratic GPU/FPS usage in Dirt2 (Nvidia surround)

[Blind Man]

Hey all, I just setup my Nvidia Surround setup with my GTX470's and am slightly confused at something happening while I am playing Dirt2. I will be going along fine at a solid 60 fps, and suddenly my fps usage will drop to 30-32, and both GPU's drop down to only running at around 54% usage (reported from MSI afterburner). I have tried various levels of AA thinking it could have been not enough VRAM but this is only a problem at 8x AA (drops to 1fps). 4x/2x/0x AA all play the same. Running at 5760x1080, w/ bezel correction.

This problem happens reliably outside of a race. Inside the trailer i get the FPS/GPU usage drop but as soon as i go outside the FPS/GPU usage jumps right up

 

[Plumber4life]

Uninstall the rapture drivers for sound, then it probably will work fine.