I have an Asus DUAL-RX580-O8G that's driving me crazy.
First of all, i have no signal when setting DisplayPort 1.2 on my monitor's OSD, but it works if i set it to 1.1 (tried with 4 different cables, both VESA certified and not and three different monitors).
Second, i have a 50/50 chance to get a no signal when switching from desktop mode to fullscreen mode and viceversa (e.g. when starting or quitting a game) or when I change a resolution in-game. This problem became worse and worse with time. However, once the game is up and running I have absolutely no issues: temperatures under ~78°C, spinning fans and high clocks for hours.
I tried basically everything: enable/disable FreeSync, underclock, overclock, undervolt, overvolt, clean driver reinstall with AMD Clean Utility, DDU, tried drivers from 17.x to 18.x and 19.1.1.
Once I've also seen black screen + artifacts.
The only way I have to restore back the signal is to force a shutdown or suspend the PC.
The PSU is a 750W 80+ gold.
Bought a brand new RX Vega 64 and DisplayPort 1.2 still doesn’t work, but other than that I have no issues at all. The RX 580 was definitely faulty.