Using latest Nvidia drivers, playing in 1080p all on full getting 45fps average with 1 card and a stuttery 45fps with 2 cards!
This is with 2 GTX 670FTWs
All I can suggest is try slightly older drivers for now and see which one works best. And make sure it's all up to date in term of patches which Origin should download automatically. Not much else I can think of than just wait until NVIDIA sort their drivers out.