To be honest the FM3+ platform is weak, any cpu on that platform will hold back a GTX1070 @ 1080p and probably even if running 1440p. If you want to allow your 1070 to meet it’s full potential it is time to move to a modern platform but that will require a new motherboard/RAM/CPU.
You could look at older Intel setups that support DDR3, this would allow you to reuse your RAM but you will need a new motherboard. However I don’t recommend this as you are investing in already outdated hardware.