I have had the Sapphire RX580 Pulse installed in a mid-2012 Mac Pro 5,1 for a number of months now. Works fine, albeit with the "no boot screen" quirk as is well-known. My challenge with this card began on the last update in High Sierra to 10.13.6. Before the update, I was using both display port-outs on the card with no issues on dual Dell UP2718Q monitors. After the update, only the HDMI ports on the card appear to be providing a signal to the monitors. After upgrading to Mojave, same curiosity persists. Not a huge issue, but certainly one that has me scratching my head. Has anyone else experienced this or a similar issue?