Comparison of XFX Speedster MERC 310 Radeon RX 7900 XT video card vs XFX Speedster MERC 319 Radeon RX 6900 XT Ultra Gaming video card by specs 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 XFX Speedster MERC 319 Radeon RX 6900 XT Ultra Gaming runs at 1.500 GHz base clock speed and has 16 GB of GDDR6 memory. The weight is different, -- vs --. The TDP of the first video card is 300 W, and the second is 300 W . Compare the benchmark results to find out which video card is better.