Running on a MSI 760GMA-P34(FX) mobo and 1000w power supply. Will be upgrading to the 16 GB of ram. Not looking to break the bank on this one but just to enjoy casual gaming in my downtime. Help is appreciated.
If you do not wish to spend too much then the best bet is either a RX570 or RX580. the 570 is pretty much the best bang for your buck right now as they a quite cheap and even cheaper if you want to get a used one usually <90$. It's still a solid card and a solid upgrade for you, although getting slightly outdated now but can play pretty much any game 1080p60fps at reasonable settings.
1660 ti is almost overpriced with the 5600xt out and the 1660 super so close in performance. That said, on fx, about the fastest you want to go is 570 or 580. Otherwise, you are going to bottleneck your CPU.