The XFX Radeon RX 590 Fatboy OC+ graphics card ships at 1580 MHz on the GPU boost clock, but is guaranteed to manually overclock to 1600 MHz.
We used Wattman in AMD Radeon Settings to overclock the XFX Radeon RX 590 Fatboy graphics card and was able to get a 4.5% overclock on the GPU frequency. The default clock speed on the Fatboy is 1580 MHz and with the 4.5% frequency boost it meant that the clock was now at 1650 MHz. We were able to max the slider out on the 8GB of GDDR5 memory, so we were running at 2250 MHz (9Gbps) instead of 2000 MHz (8Gbps). This is a nice 12.5% increase in the memory clock speed! We left the voltage control on automatic, but did increase the power limit as high as it would go.
The XFX Radeon RX 590 Fatboy scored 5,171 points in the overall test on 3DMark Time Spy and we were able to improve that to 5,463 points. This is a 5.6% performance increase thanks to the combined GPU and GDDR5 overclock.
The overclock on the Radeon RX 590 Fatboy yielded a nice performance boost, but we were unable to pass up any other models with the overclock.
Although in Rainbow Six Siege the overclock helped the XFX Radeon RX 590 Fatboy pass up the NVIDIA GeForce GTX 1070 Founders Edition model at both 1080P and 1440P resolutions. We saw a performance gain of nearly 15% on this game title at 1080P.
Overclocking does increase the power draw though as we saw right around a 20 Watt increase in power draw on the system at the wall. This means we were sucking down about the same amount of power as the NVIDIA GeForce RTX 2080 cards. The RX 590 Fatboy is hungry and you got to feed this beast!