I'm not sure how much info you guys would need to give a comprehensive answer so let me know.

I just bought a GTX 1060 to replace (or add to for now) my old (don't laugh) GTX 660.

Yet to install it, and need to know if I can use both in my system (as in, does it support that set up) but also, is it worth running them both? I'm sure if my CPU/Motherboard combo is insufficient, running two cards might not yield much improvement.

Processor is i7-4770, under PCI-E it says max supported x16

I intend to use Vray RT for now.

Would also like to know of another graphics card that would pair well with the 1060 if I decide to replace the 660. Again, assuming my set up could accommodate it.