Comparison of MSI Radeon RX 6600 MECH 2X 8G video card vs PowerColor Radeon RX 6900 XT video card by specifications and benchmarks. MSI Radeon RX 6600 MECH 2X 8G runs at 1.626 GHz base clock speed and has 8 GB of GDDR6 memory, while video card PowerColor Radeon RX 6900 XT runs at 1.825 GHz 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.