Different GPUs in a System

Is it possible to use different gpu cards for cuda at the same time (e.g. C1060 with k20)?

You’d have to add the logic to your code to switch between cards and queue your kernels accordingly, but yes, it’s possible. Just remember to compile your code with the correct arch flags for the graphics card you’re trying to support. For this case I believe it is sm_20 and sm_35.