CPUs generally are more then fast enough for any card at any resolution, especially new generation ones, thats why a CPU can last years and years before seeing a bottleneck. The real question is if the RX580 is powerful enough for your needs. The RX580 is rough as powerful as a GTX1060 so if your looking to run 1080P at a stable 60 FPS its more then capable. You can also probably achieve 1440P at a 60FPS with some drops in more demanding titles if you adjust settings.