Expect the vega 56 to be about 33% faster in game than the RX 580 in a stock vs stock setting. (I have both the rx580 and Vega 56). Overclocking the vega 56 and flashing a vega 64 bios onto it really starts to make the vega 56 shine. I got my rx580 used for $100 and my vega 56 used for $230, steer away from the Gigabyte gaming OC version of these cards. Its the card I bought used (for parts or not working) luckily it's under warranty and just sent mine back a few days ago for a RMA.