670 SLI vs gtx 780

So you have none of the above cards and you want some help choosing? I would say the 780. 670's in SLI (especially 2GB) won't compete with a 780, if you factor heat, noise and power consumption in. The performance is usually around the same though.

I would highly recommend the 780 over the two 670's. Then you can SLI 780's later if you wanted.