*Possible* solution for black screen over Display Port after upgrade to Mojave

Aug 22, 2017
Z390 Designare
RX 580
  1. iMac
Mobile Phone
  1. iOS
For those who are using Display Port to connect their monitor and are getting a message saying "Entering Power Save Mode" on their display after Clover boot loader screen, I wanted to share my experience. I have spent 3 days trying to figure out the issue with a lot of help from @pastrychef @Stork and @manHands. All 3 have offered very good advice and for those struggling with issues, I would strongly suggest that you read through some of our posts and the links/suggestions they provide and implement them, provided you have a similar set up as me.

I had previously attempted to implement native display brightness using F1 and F2 keys and read somewhere that I should update the firmware for my DELL U3415W which enables Display Port v1.2 connectivity among other things. Using my Windows 10 partition I installed firmware and enabled DP1.2 This worked well in High Sierra 10.13.6, however once I upgraded to Mojave, I had to switch my monitor input to HDMI (it took me a while to figure this one out). I spent hours updating kexts / modifying my Clover settings to no avail. I decided to read the manual of my DELL monitor and found that there was a setting for enabling and disabling DP1.2. Sure enough, once I disabled DP1.2 I got video over Display Port. Lesson learned.

I am not sure why High Sierra [I went through the trouble of making a separate install of HS 10.3.6 on another drive] :crazy: and DP1.2 play nice, but Mojave doesn't but this solved my issue and might help someone exhibiting similar behavior.

Bottom line, if you're running Mojave, disable DP1.2 and/or restore your display to factory settings using OSD menu. Now, if I could just figure out the preview situation with jpg and get my Slate VRS8 Thunderbolt going, I would be set. :think: