Comparison of Sapphire Toxic Radeon RX 6900 XT Extreme Edition video card vs ASRock Phantom Gaming X Radeon RX Vega 56 video card by specifications and benchmarks. Sapphire Toxic Radeon RX 6900 XT Extreme Edition runs at 1.825 GHz base clock speed and has 16 GB of GDDR6 memory, while video card ASRock Phantom Gaming X Radeon RX Vega 56 runs at 1.156 GHz base clock speed and has 8 GB of HBM2 memory. The TDP of the first video card is 430 W+ 43 %, and the second is 210 W. Compare the table of benchmark results to find out which graphic card is better.