3DMark Fire Strike is a showcase DirectX 11 benchmark designed for today’s high-performance gaming PCs. It is our [FutureMark’s] most ambitious and technical benchmark ever, featuring real-time graphics rendered with detail and complexity far beyond what is found in other benchmarks and games today.
It's a decent start for the Phantom Gaming X RX 580. It is marginally behind the higher-clocked Sapphire Nitro+ Limited Edition (1408MHz vs 1450MHz) but that is to be expected.