Comparison of ASRock Radeon RX 5700 Phantom Gaming D 8G OC video card vs XFX Speedster MERC308 Radeon RX 6600 XT BLACK Gaming video card by specifications and benchmarks. ASRock Radeon RX 5700 Phantom Gaming D 8G OC runs at 1.610 GHz+ 10 % base clock speed and has 8 GB of GDDR6 memory, while video card 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. The TDP of the first video card is 180 W, and the second is 160 W. Compare the table of benchmark results to find out which graphic card is better.