Enabling GPU Transcode on SLI setups:
go to nv control panel for the rage profile, select cuda gpus available, select use this gpu and select only one, save, done. Latest nvidia drivers and rage patched here. So far this worked for me and I didn't need to physically remove a video card (which I refuse to do on basic principle)
Hope it works for you
*UPDATE...
Well for what it's worth it makes the game run worse for me lol. GPU enabled gives me a much much higher benchmark but the game stutters, looks like it loses framerates, just not smooth. Turn it off? Way lower benchmark but the game runs awesome LOL (go figure)
With these specs i benchmark 60 with GPU Transcoding OFF and 140 with GPU Transcoding ON:
AMD Phenom II X6 1090T Black Edition Thuban 3.2GHz
ASUS M4N98TD EVO AM3 NVIDIA nForce 980a SLI ATX AMD
2ea EVGA 2GB GTX 560TI running in SLI
G.SKILL Ripjaws X Series 16GB (4 x 4GB) SDRAM DDR3 1600
RAIDMAX RX-1200AE 1200W ATX12V v2.3 / EPS12V SLI Certified
WD Caviar Black 500GB 7200 RPM Hard Drive 3GB SATA
Creative Sound Blaster X-Fi Titanium Fatal1ty Professional
Windows 7 Premium Home Edition 64 bit