3 GPU, 3 applications and 3 separate monitors (not surround) - only one GPU active


I run 3 applications (OpenGL) simultaneously and i need them to use one GPU each,
every GPU is connected to a monitor (no surround setup).

System: Win7, 3 x GTX 780

No matter how i configure the cards (disable sli / activate all / surround) it does not work as expected - one GPU does all the work (with 99% load, the others 0-10% load).

The 3 application windows start up on their respective monitors.

How can i force each application to use a separate GPU?

If i run 3-way sli, all the cards work on full load, but the performance is still the same as if only one card was running.

[ Details:
It is especially when loading new geometry that graphics lags severely with 3 apps running, framerate dropping as low as 5 FPS.
The applications are not CPU bound.
The 3D worlds have up to 24 million triangles.

I just switched out the 3xGTX 780 cards for 3x AMD R9 290X and then it works as expected. However, i would still prefer to use the Nvidia cards as they would give a good deal better FPS if they could run one application each.

So still hoping for a solution to this problem. ]

Best regards, Ola

[moved content of this post into original question.]