Comparison of XFX Speedster MERC 319 Radeon RX 6900 XT Limited Black Gaming video card vs ASRock Phantom Gaming X Radeon VII 16G video card by specs and benchmarks. 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, while video card ASRock Phantom Gaming X Radeon VII 16G runs at 2.150 GHz+ 18 % base clock speed and has 16 GB of HBM2 memory. The weight is different, -- vs --. The TDP of the first video card is 300 W, and the second is 300 W . Compare the benchmark results to find out which video card is better.