Comparison of XFX Radeon RX 580 GTS Black Edition 8GB video card vs XFX Speedster MERC 319 Radeon RX 6900 XT Black Gaming video card by specifications and benchmarks. XFX Radeon RX 580 GTS Black Edition 8GB runs at 1.257 GHz base clock speed and has 8 GB of GDDR5 memory, while video card XFX Speedster MERC 319 Radeon RX 6900 XT Black Gaming runs at 1.950 GHz+ 7 % base clock speed and has 16 GB of GDDR6 memory. The TDP of the first video card is 185 W, and the second is 300 W. Compare the table of benchmark results to find out which graphic card is better.