AMD Radeon HD 7770 third monitor not working (OpenCore)

[Chris07]

Hello,

I am not sure where to start or what files I need you to have for helping me.
I successfully installed macOS Monterey 12.1 (21C52) on my PC, but the one thing I am not able to fix after a lot of hours trying to find a solution for, is that my third monitor won't work. My graphics card (AMD Radeon HD 7770 ghz edition) got 1 HDMI, 1 DP & 1 DVI port, and the DVI port is the problem. When I connect the cable to the monitor (yes, I've tried several other cables), the monitor blinks every 5-10 seconds.

WhateverGreen and Lilu (both at latest version) is loaded under boot and I've tried almost every single boot args. My config.plist got the following boot-args: -v keepsyms=1 dk.e1000=0 debug=0x100 radpg=15 -raddvi -lilubetaall -wegdbg -liludbg

-raddvi seems to do nothing, while radpg=15 is mandatory for this specific card to work.

Is there anyone here that are able to help me regarding this issue?

Thanks in advance

CPU	Intel Core i7-11700KF
Motherboard	ASUS ROG STRIX Z490-G GAMING WIFI
SMBIOS	iMac20,1
OpenCore version	0.7.7

 

[ulisch]

Hey Chris,

seems like we are sitting in a similar boat! At least at first look I am suffering the same thing, although I have slightly different HW: Radeon hd7750 with 3 ports (DP, DVI, HDMI), running Monterey latest release with OC 0.79. I run two displays, one off DP, one off of DVI.
DP works pretty reliably with flag radpg=15, DVI only works, when display is disconnected and reconnected till after the logon screen, otherwise it blinks on and off, sometimes colorstripes.
Tried various other boot arg, e.g. -raddvi, no help.
Previous installation, same system, with Mojave under Clover was running fine, needed the mandatory radpg=15, that was it.

Maybe you try the connect disconnect game/ monitor power button. Not pretty! Will try the DP with HDMI combo.

Mobo: GA H81M
Proc i5 Haswell
Gra Radeon HD 7750
Smbios iMac17,1
OC 0.79
Monterey (latest release)