Comparison of XFX Radeon RX 580 GTS Black Core Edition 8GB video card vs Gainward GeForce GTX 1660 Pegasus video card by specifications and benchmarks. XFX Radeon RX 580 GTS Black Core Edition 8GB runs at 1.257 GHz base clock speed and has 8 GB of GDDR5 memory, while video card Gainward GeForce GTX 1660 Pegasus runs at 1.530 GHz base clock speed and has 6 GB of GDDR5 memory. The TDP of the first video card is 185 W, and the second is 120 W. Compare the table of benchmark results to find out which graphic card is better.