Vulkan and DirectX 12 expose the best the RX 480 has to offer, increasing performance by as much as 20%. Here's a few highlights of reviews with good coverage of these modern
RX 480 vs GTX 1080 Max-Q Game Performance Benchmarks (i7-6700K vs i7-6700K) - GPUCheck United States / USA
Mathematical analysis of the RX 480 performance in comparison with Nvidia's upcoming GTX 1060 (and a few observations) : r/Amd
AMD explains image quality in AOTS Radeon RX 480 CF vs GTX 1080 demonstration | VideoCardz.com
AMD Radeon RX 480 review: the best $200 GPU you can buy today - ExtremeTech