Comparison of Sapphire Pulse Radeon RX 6600 video card vs XFX Speedster MERC 319 Radeon RX 6900 XT Ultra Gaming video card by specifications and benchmarks. Sapphire Pulse Radeon RX 6600 runs at 1.626 GHz base clock speed and has 8 GB of GDDR6 memory, while video card XFX Speedster MERC 319 Radeon RX 6900 XT Ultra Gaming runs at 1.925 GHz+ 5 % base clock speed and has 16 GB of GDDR6 memory. The TDP of the first video card is 132 W, and the second is 300 W. Compare the table of benchmark results to find out which graphic card is better.