NVIDIA GTX 460's: SLI black screen issue

Question

I have 2 GTX 460's and a EVGA FTW3 motherboard. I have the 2 cards in the first 2 slots, and have also tried 1 + 3 with no luck.

When I have SLI disabled, games seem to run perfectly fine- albeit slower than I would like.

When I enable SLI, there is an odd problem where whenever I load up a game in full screen, or the content within the game changes (e.g. in 3dmark vantage, every time a new test starts up this occurs) the screen goes black.

The odd thing is that if I cycle through my monitor's inputs circle back to the VGA/computer input, the picture shows up. I have tried re-installing windows, re-installing the NVIDIA drivers etc with no luck.

Any ideas? As noted, this only occurs when SLI is enabled.