Comparison of ASRock Radeon RX 6600 Challenger D video card vs XFX Speedster MERC 319 Radeon RX 6700 XT Black Gaming 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 XFX Speedster MERC 319 Radeon RX 6700 XT Black Gaming runs at 2.457 GHz+ 6 % base clock speed and has 12 GB of GDDR6 memory. The TDP of the first video card is 132 W, and the second is 211 W-8 %. Compare the table of benchmark results to find out which graphic card is better.