Normally when you add an Discrete GPU card (RX570) to a motherboard with a APU (Processor with Integrated Graphics), the Motherboard's BIOS automatically makes the GPU Card it main Display Adapter and not the Integrated Graphics unless you specifically have in BIOS set to use strictly the Integrated Graphics.
So you can use the RX570, which is more powerful than the APU graphics to play DOTA 2 or you can remove or disable the RX570 (In BIOS) and just use the Integrated Graphics instead.