gt 520 and gtx 550 ti

Solution
What you are wanting to do (running the processing power of 2 GPUS together as one "super" gpu) is called SLI.

Even if those cards supported it (which they don't) you cant mix and match chipsets. You have to use 2 of the same chipsets, so two GTX-960s for example.
What you are wanting to do (running the processing power of 2 GPUS together as one "super" gpu) is called SLI.

Even if those cards supported it (which they don't) you cant mix and match chipsets. You have to use 2 of the same chipsets, so two GTX-960s for example.
 
Solution