Comparison of XFX Speedster MERC 319 Radeon RX 6900 XT Ultra Gaming video card vs AMD Radeon RX 6600M (Mobile) - 100 W video card by specifications and benchmarks. 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, while video card AMD Radeon RX 6600M (Mobile) - 100 W runs at 2.068 GHz base clock speed and has 8 GB of GDDR6 memory. The TDP of the first video card is 300 W, and the second is 100 W. Compare the table of benchmark results to find out which graphic card is better.