Comparison of XFX Speedster MERC 310 Radeon RX 7900 XT video card vs PowerColor Liquid Devil Radeon RX 6900 XT Ultimate video card by specifications and benchmarks. XFX Speedster MERC 310 Radeon RX 7900 XT runs at 1.500 GHz base clock speed and has 20 GB of GDDR6 memory, while video card PowerColor Liquid Devil Radeon RX 6900 XT Ultimate 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.