Working AMD graphics card, but flickers on right screen edge, if 120 Hz is enabled

Dec 22, 2015
R9 380X
MacBook Pro
Mobile Phone
Android, iOS
Hey guys!

I had a GTX 1080, but I need Mojave for work and since NVIDIA can't get their act together...

So I rolled back to my older Sapphire Radeon R9 380X 4 GB NITRO, since AMD and Apple seem to be BFFs now. It worked out of the box, I was able to upgrade to Mojave without a problem.

However, now I have a slight screen flicker on the right side of the screen, if I use my regular monitor with it (Alienware AW3418DW) on the DisplayPort.

If I plug in another FullHD Monitor on HDMI, the flicker is non-existent. Sadly, the AW3418DW doesn't even work on HDMI. Dual booted Windows works perfectly, no flickering whatsoever. BIOS has the internal GPU as first boot graphics, I removed all injects from the Clover settings.

System Definition: iMac 14,2

Boot arguments: dart=0

Installed Kexts (all via Clover EFI folder):
  • USBInjectAll 0.7.1 (I know I should somehow do a proper USB patch, but I didn't get around doing it yet, since I didn't understand it on first read... :D)
  • FakeSMC + Sensors 1800
  • CPUFriend 1.1.6
  • RealtekRTL8111 2.2.1
  • Lilu 1.3.5
  • Whatevergreen 1.2.7
I read, that changing the System Definition might be a solution. Can I do that without destroying working iMessage, iCloud, etc?

Edit: Narrowed it down to the refresh rate. I had it on 120 Hz. If I turn it down to 100 Hz, it works without the flicker!
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