Your video cards ( GTX 560 Ti ) and that too at SLI, is really good. You don't have to upgrade it, or at least not now.
As everyone else said, you have to change a ini file, that is in the CVAR groups.
And as for your question, no, your problem won't be resolved if you had better GPUs. That is , unless you have changed the view distance, then performance won't be affected.( at least not much FPS drops )