The title explains itself. would an i5 3340 bottleck a gtx 1660? Which would be the best gpu to pair with that CPU? An rx 580?
You're going to have a tough time trying to get games to run without lag with those GPU's. In fact you shouldn't be going anything above a GTX750Ti or a GTX1050Ti. Might I ask what your current system's specs are? List them like so:
CPU:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS: