Comparison of XFX Radeon RX 590 Fatboy Core Edition 8GB video card vs PowerColor Radeon RX 6900 XT video card by specifications and benchmarks. XFX Radeon RX 590 Fatboy Core Edition 8GB runs at 1.469 GHz base clock speed and has 8 GB of GDDR5 memory, while video card PowerColor Radeon RX 6900 XT runs at 1.825 GHz base clock speed and has 16 GB of GDDR6 memory. The TDP of the first video card is 225 W, and the second is 300 W. Compare the table of benchmark results to find out which graphic card is better.