Two GPU question

[roughavoc]

The situation:
I do 3D work and when it comes to rendering, I use V-Ray RT CUDA which uses 100% of my GPU which causes the entire system to lock up and for look development it is very annoying having my cursor lag and skip around the screen whilst it is rendering away. The software has an option to put it on low thread priority but the issue is that it reduces the performance of the rendering by an amount it is quicker to just use CPU rendering which defeats the point 

Here is what I want to do:
You can solve the whole system lagging to a laggy mess by using a separate GPU for the rendering and one for Windows, that is fine as I have a GTX 460 sitting here collecting dust

The issue I think I'll face:
If I plug both GPUs in and connect the screen to the 1070 I have haven't done anything, the system will still be laggy as the one GPU is still doing the rendering as well as the Windows UI. BUT if I plug the screens into the GTX 460 it should work all fine. But what happens when I want to game? Will I be limited to using the GTX 460 level of performance? or is there a way to route the processing from the GPU somehow through the GTX 460 videos output? or will I have to actually change the cables every time I wanna play something?

[Godlygamer23]

In the NVIDIA drivers, you can configure which GPU can be used for CUDA processing.

[Electronics Wizardy]

Your limited to the performance of the 460 for this use. Also the fermi cards now are using older drives so you can't use the newest drives.

[roughavoc]

The CUDA processing isn't the issue, V-Ray already has that option

[roughavoc]

Just now, Electronics Wizardy said:

Your limited to the performance of the 460 for this use. Also the fermi cards now are using older drives so you can't use the newest drives.

Drivers.. I didn't even think about that... 

I guess another question would be, is there a way to limit a program's GPU usage? Like you can limit FPS or core affinity, is there a way to do that for GPUs?

[Electronics Wizardy]

19 minutes ago, roughavoc said:

Drivers.. I didn't even think about that... 

I guess another question would be, is there a way to limit a program's GPU usage? Like you can limit FPS or core affinity, is there a way to do that for GPUs?

Not easily due to how gpu's are controlled.