Comparison of XFX Speedster MERC 310 Radeon RX 7900 XT Black Edition video card vs PowerColor Red Devil Radeon RX 6800 XT Limited Edition video card by specifications and benchmarks. XFX Speedster MERC 310 Radeon RX 7900 XT Black Edition runs at 1.500 GHz base clock speed and has 20 GB of GDDR6 memory, while video card PowerColor Red Devil Radeon RX 6800 XT Limited Edition runs at 1.900 GHz+ 4 % base clock speed and has 16 GB of GDDR6 memory. The TDP of the first video card is 300 W, and the second is 300 W. Compare the table of benchmark results to find out which graphic card is better.