I’m running Seti@home.
Running WIn 7 X64 driver 190.38 I only see one CUDA device when SLI is off.
When I select Quad SLI there are 4 CUDA devices detected.
It works just the opposite from what you would expect.
But the computer becomes SLOOOOW beyond belief.
When I used only 1 card everything worked fine, 2 detected in non SLI and nothing slow about it.
In XP 64 everthing works fine as well 4x detected and running properly.