What resolution? Which Corsair 650w, hopefully not the VS or CXM. You may also want to consider a cpu upgrade as quad cores are struggling in some newer high end games.
There is, imo, a good deal of difference, but you have to decide if that difference is worth the added cost. If you are looking at higher end GPU's, and 1080p gaming, I would say the 3600 is the way to go.thank you is there much different between the 2600 and 3600