VRAY RT - slows down my system even with only 1 out of my 2 gfx cards selected?

[nickdk]

I'm using the newest Vray release and I have problems with Vray RT. I have selected only 1 of my gfx cards (Nvidia GTX580x2) as the active open CL device. But my system slows down as if I were using the CPU's? I have made sure that RT is setup to use my GPU.

Is there anything I can do to fix this? The great thing about having the RT window open to adjust lighting and so on disappears when my system is so slow.