Comparison of PowerColor Red Devil Radeon RX 6600 XT video card vs XFX Speedster MERC 319 Radeon RX 6900 XT Limited Black Gaming video card by specifications and benchmarks. PowerColor Red Devil Radeon RX 6600 XT runs at 2.188 GHz+ 11 % base clock speed and has 8 GB of GDDR6 memory, while video card XFX Speedster MERC 319 Radeon RX 6900 XT Limited Black Gaming runs at 2.150 GHz+ 18 % base clock speed and has 16 GB of GDDR6 memory. The TDP of the first video card is 160 W, and the second is 300 W. Compare the table of benchmark results to find out which graphic card is better.