Comparison of XFX Speedster MERC308 Radeon RX 6600 XT BLACK Gaming video card vs ASRock Radeon RX 6700 XT Challenger D 12GB OC video card by specifications and benchmarks. XFX Speedster MERC308 Radeon RX 6600 XT BLACK Gaming runs at 2.188 GHz+ 11 % base clock speed and has 8 GB of GDDR6 memory, while video card ASRock Radeon RX 6700 XT Challenger D 12GB OC runs at 2.330 GHz base clock speed and has 12 GB of GDDR6 memory. The TDP of the first video card is 160 W, and the second is 230 W. Compare the table of benchmark results to find out which graphic card is better.