The cpu sets the fps limit, not the gpu. The gpu deals with resolution and details. If your games are maxing out that Pentium's ability, you could move to a RTX2080ti and get no real change. The only thing that's going to be different really moving from a 1050 to a Rx580 is the possible level of detail. In games where it was set on medium, you'll get high to ultra, but the fps won't change much as it's limited by the cpu.
If you want higher fps, you'll need to move up in ability, something like an i5-8400, but realize that'll open up the power draw on that Rx and that 430w Evga is on the small side.