Reports on Retail Radeon RX 580 8GB in Mac Pros (macOS 10.12.6 and 10.13.x)

Added a sixth report on stock (not flashed) Radeon RX 580 8GB in a Mac Pro.
Latest report is on a Sapphire Nitro+ RX 580 8GB in a Mac Pro 5,1 (12 core) running macOS 10.13.5. (4 others on Sapphire Pulse model, 1 on a Sapphire Radeon RX 580 Nitro+ Special Edition.) Native driver support in macOS 10.12.6 or later and supports Apple Metal. (Not flashed so no boot screen.) Below the report are notes on macOS installs requiring an OEM mac rom card and reminder on the Radeon 7950 ROM switch settings.