Wrong resolution on 21:9 - 2560x1080p with HD 4600 via HDMI

[domenics]

Hey guys, iam pretty new to this forum and built my first hackintosh successfully. It should be noted that I use clover instead of the unibeast methode from the installation guide.
during my installation i used a small 720p display without any problems, but i switched yesterday to a 21:9 LG screen with 2560x1080p. My problem is that the resolution is still 1920x1080 and so pretty distorted/extended. I read that osx needs for these resolutions a DP cable. however neather my mobo nor my display has display port. Any idea what to do? should i swith to some adapter o smth like that?
or do i have to make changes in my config.plist

my specs:
gigabyte ga h97n wifi (2HDMI 1xDVI dual link)
i3-4370
hd 4600
samsung ssd
lg 25um57-p (2x HDMI)
OSX 10.11 El Cap with Clover UEFI and dual boot WIN 10 (no problems with 21:9 display resolution on windows with hdmi)

thank you and greetings from germany

 

[Fl0r!an]

HDMI support tends to be buggy beyond 1080p, yes. Did you try SwitchResX or one of the manual ways add custom resolutions? Maybe that'll work...

 

[domenics]

i changed the resolution directly in clover to 2560x1080p but after a reboot it was still "normal" 1920x1080p. after changing my resolution with SwitchResX there were black bars above and below, so no realy 21:9, more a 26:9 or something like that.. i think the program just squashed it smaller in the height.
any idea what i can do? do you think a dvi to hdmi adapter will resolve my issue?

 

[pelezim]

I face the same problem

 

[raz.hun]

I use dedicated graphics, but couldn't get higher resolution than 1920x1080 using HDMI. With a DVI to HDMI cable, it works fine.

 

[schwingel]

hey, maybe you could try this solution

http://www.tonymacx86.com/graphics/175973-solved-el-capitan-2560x1440-hdmi-ga-h97-d3h-hd4400.html

 

[domenics]

THANK YOU VERY MUCH! I just ran the first step, the mac-pixel-clock-patch and now the resolution is perfect!
https://github.com/Floris497/mac-pixel-clock-patch

 

[schwingel]

great!!! so... probably only the first step is necessary!!

 

[domenics]

does anyone know how to change the boot screen resolution to my format?

 

[schwingel]

are you using clover?

try change boot from UEFI to legacy or vice-versa. Its working to me but I'm not sure what I did to fix.