Apple Cinema Display 24" and Radeon HD 6870 with Mini DP not working on Clover :(

[benjaminmlynek]

Hi

I have just reinstalled my Hack with Clover and Yosemite. I've used a Samsung 23" screen though DVI and everything is running fine. But when i wanted to switch back to my ACD and connect it with Mini DP, it doesn't work. The screen worked when i ran Mavericks with Unibeast/Multibeast. When i plug in my DVI screen and boots and then take the DVI screen out and plug the ACD in afterwards it works fine.

When just booting with ACD it shows the login screen in yosemite but like 1/4 of the screen is only visible in the upper right corner and it's like stuttering.

Have anyone experienced the same and have a fix for it?

My motherboard is a: GigaByte GA-Z68XP-UD3 (rev. 1.0).

 

[Stork]

Yes, I have a 23" ACD (DVI). The Award BIOS and the ACD don't play well together. The Award BIOS wants to drive the screen at a small resolution than the ACD will go. My ACD does play well with the UEFI BIOS of Ivy Bridge and newer. So, use your Samsung monitor when you want to get into your BIOS.

 

[benjaminmlynek]

The problem isn't to get into my BIOS, the problem is when it is has booted to the login screen. Then there's no picture, when the ACD is connected. Only if the DVI display is connected first then there's picture on the ACD I just want to use the ACD and lock away my samsung screen But that isn't possible at the moment. Maybe i need some Clover configuration or something?

 

[benjaminmlynek]

It looks like this when booting with my ACD. Anyone have had the same problem and know how to fix it?

 

[Stork]

Try booting with the flag "GraphicsMode=1920x1200x32". If that works, put it into your /Extra/org.chameleon.Boot.plist file.

Update: I just remembered you use Clover, so the above may have to be accomplished in another manner in Clover. (I don't use Clover.) Another thought, until Mavericks, I had to use the Framebuffer boot commands (AtiConfig & AtiPorts) to enable my Gigabyte HD6850 to work correctly - driving two DVI monitors with the 6850 DVI and DP (to DVI active adapter). However, I didn't need the "Ati" boot commands with Mavericks and Yosemite. You may have to explore using those flags (see the framebuffer sticky thread by tonymacx86 in this forum section).

 

[benjaminmlynek]

I've tried with all the Framebuffer personalities without any luck The weird thing is when i boot in to yosemite just using the DVI screen. And plug in the ACD it works perfect. So it's something with the mini displayports on the HD 6870 when booting. I just can't seem to figure this out :S

 

[Fl0r!an]

Over at netkas.org I've read about an incompatibility between the HD 5870 and the DisplayPort Apple displays. Maybe this problem still persists with the HD 6870?
Can you verify that the miniDisplayPort you're trying to use works with other screens?

 

[Stork]

I've tried with all the Framebuffer personalities without any luck The weird thing is when i boot in to yosemite just using the DVI screen. And plug in the ACD it works perfect. So it's something with the mini displayports on the HD 6870 when booting. I just can't seem to figure this out :S

Now that I think of it...my 6850 is connected to a 27" Dell (U2711) @ 2560x1440 via DP to DVI active adapter and a 24" HP ZR24 @ 1920x1200 via the DVI. IIRC, the boot up BIOS screen and boot loader does appear on the HP monitor driven by DVI and the Dell doesn't display anything until the Desktop appears. So, it could be the card's VBIOS automatically drives the DVI connector upon boot up until OS X takes over with it's drivers. (Unfortunately, I can't confirm my suspicions since I'm away from the system for 6 weeks.)

Fl0r!an is probably right, too. Interesting...

 

[benjaminmlynek]

I have used the same display before i changed to Clover bootloader, and it worked perfectly with the HD 6870 . I hope there's a fix for this. Are there any other graphics cards who works out the box with mini DP?

 

[Fl0r!an]

Okay, good to know it's not your card being physically incompatible.

Did you also try to boot without any graphics injection? (InjectAti=False, no Framebuffer). Should usually work as good as a specific framebuffer in Yosemite.
The correct FB for your card should be 'Duckweed', but I assume you already tried that before...

Regarding the cards: Supported Nvidia cards can be found in the buyers guide. For AMD, pretty much any common card should work OOB in Yosemite, e.g.

- HD 7770/R7 250X (not recommended, needs Info.plist mod until someone fixes the bootloader injection code)
- HD 7850/7870 / R9 270(X)
- HD 7950/R9 280
- HD 7970/R9 280X

All of them are available with mDP connectors. More modern cards (e.g. Tonga (R9 285/R9 380) or Hawaii (R9 290/390)) will also work, but drivers still have some bugs so I wouldn't recommend them.