Comparison of ASRock Radeon RX 6600 Challenger D video card vs ASRock Phantom Gaming X Radeon RX Vega 56 video card by specifications and benchmarks. ASRock Radeon RX 6600 Challenger D runs at 1.626 GHz base clock speed and has 8 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 132 W, and the second is 210 W. Compare the table of benchmark results to find out which graphic card is better.