Comparison of GIGABYTE Radeon RX 7900 XT GAMING OC 20G video card vs Sapphire Radeon RX 6800 XT video card by specifications and benchmarks. GIGABYTE Radeon RX 7900 XT GAMING OC 20G runs at 1.500 GHz base clock speed and has 20 GB of GDDR6 memory, while video card Sapphire Radeon RX 6800 XT runs at 1.825 GHz base clock speed and has 16 GB of GDDR6 memory. The TDP of the first video card is 300 W, and the second is 300 W. Compare the table of benchmark results to find out which graphic card is better.