Can't get 4k/120 working on hack

[MysticalOS]

First of all I have a 6900XT with DisplayPort 1.4 x 3, the hardware isn't issue on GPU.

For 2 screens I have two GP27U

When I hook them up to M1Max macbook pro they both show correct adaptive sync, 144hz etc modes.

macOS they have no adaptive sync and locked to 60hz.

My first thought was it was the systemdef, that macOS was not allowing adaptive sync or higher refresh cause it's set to iMac19,1 so I tried 7.1 MacPro7,1 and that didn't change anything. Something on hack though is limiting it to an older/slower Display Port protocol, that or just apple genuinely doesn't support 4k/120 over standard display port and only Alt DP over USB C (which is what I used on macbook pro and it worked fine)

 

[MysticalOS]

Found https://github.com/kingo132/a51m-r2-5700m-hackintosh/blob/main/fix_navi10_4k_120hz.md in my digging, seems related. If i understand this right. it's the AMD driver that is returning no for 4k/120hz regardless of what the bandwidth/feature set of displayport 1.4 is. Basically this is why my M1Max can use high refresh rates and hack pro can't.

The depth of this readme doesn't explain how to go about patching driver with whatevergreen though, although maybe they just run a custom compile of WEG. Perhaps somewhere though has more wisdom and can make sense of this information.

 

[cyl19910101]

My situation is similar, 6900 XT macOS 13.2.1, triple G3223Q, can only output 60HZ, while 144HZ in Windows.

But my M1 Max MBP can only output 60HZ as well, with 8K USB C to DisplayPort Cable,... https://www.amazon.com.au/dp/B08BXPVPPQ/, wired

 

[MysticalOS]

I read there were problems with usb c to display port. it's why I went with a display port alt mode USB-C monitor. i'm using the 2 monitors exclusively with macbook pro now and reformated the hackintosh to just a windows 11 PC. I spent 1600 on this screens, if I can't use em with hack them hack days are done. especially since performance between it and my M1 Max wasn't that far off anyways, i decided to go all in with a drive enclosure and moved all drives out of hack but the nvme which stayed in it for windows 11, now it'll be a diablo 2/4 PC. the good thing about my screen, the PC can be hooked up to display ports while MBP to USB C and all i gotta do is change input

Will I return to hack one day, depends where it goes. apple is once agian researching external gpus according to recent patent, but that doesn't mean first apple silicon mac pro will have it, it's probably a down the line type thing.