I'd say you'll have less issues with games on Linux, and better performance if you keep the GT 640 in your machine.

http://gpuboss.com/gpus/Radeon-HD-6670-vs-GeForce-GT-640

Things get a little more interesting if you at some point go for a graphics upgrade.

AMD's RX 580 is a pretty tasty card, although for pure graphics power Nvidia's expensive GTX 1070, 1080 or 1080 Ti do blow it away. If you were comparing an RX 580 to a GTX 1060 then things are a lot closer.

Quoting: g000hI'd say you'll have less issues with games on Linux, and better performance if you keep the GT 640 in your machine.

http://gpuboss.com/gpus/Radeon-HD-6670-vs-GeForce-GT-640

Things get a little more interesting if you at some point go for a graphics upgrade.

AMD's RX 580 is a pretty tasty card, although for pure graphics power Nvidia's expensive GTX 1070, 1080 or 1080 Ti do blow it away. If you were comparing an RX 580 to a GTX 1060 then things are a lot closer.

I don't plan on upgrading this machine anytime in the near future. Also, I've seen that page before, and there are a couple things that make it seem inaccurate for my situation... First, it doesn't use the correct models that I have. As I mentioned before, both of my cards have 2GB of GDDR5. Second, those results are for windows. However, using simple logic, I suppose I could translate that as the gt 640 being the definite better performer. I'm still curious about the gap though. Is mesa for AMD as proportionately good as the proprietary nvidia drivers are when compared to windows? Btw, thanks for the reply. :)

Apologies... I just double checked, and it appears my 6670 only has DDR3 memory, not GDDR5. I suppose that makes my decision then. :) Maybe I'll try to put together a cheap bitcoin rig with the 6670. Better than nothing I guess. lol. Anyway, thanks again for the reply. :)