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cMP + Sierra + GTX 1080 + HP Z27q = no 5k ?

A

ArleX

macrumors newbie
Original poster
Jul 5, 2017
5
0
Hi, I've been trying to move from my old Dell 30" monitor and jump on the HiDPI bandwagon but had no luck in the process.

My detailed setup is the following:
  • cMP 4,1 flashed to 5,1
  • MVC flashed GTX 1080 (evga ACX 3.0), with 2 DP, 2 mini DP and 1 DVI
  • Latest Sierra (10.12.5)
  • Brand new HP Z27q monitor, that should support MST to reach 5K over dual DP, linked using supplied DP cables to the 2 DP ports of the GTX1080.

My intial action was to disable SIP and set the nvram parameters to enable MST in nvidia driver as indicated elsewhere ("boot-args=kext-dev-mode=1 nv_spanmodepolicy=1").

Z27 display is properly setup for Display Port 1.2 (no other option on the OSD to explicitely enable MST).

I understood that fumbling with display overrides files was not necessary under Sierra as it contains the definition for the HP display.

I never got this setup to work in 5k, even if I think I tried all the full size DP-links order and power-on sequence combinations. I always see two HP Z27 displays appearing unders the Display pane of system Preferences. The second one being with an odd 2560 x 2880 resolution but not displayed on the physical screen.

At one time I selected the mirror mode, "Optimize for the second display" in the pull down menu, and got a 5k image on screen but with 2 duplicated Desktops and an instable image travelling across the screen. Since that time, I have a flickering of the display and some persistence of my Desktop behind the OSD for example, even after a very long power cycle of the screen (several hours). I can't even find a way to get back to a clean 4K mode.

Did any of you found a way to get 5K on a cMP with a GTX 1080 ? Should I try to use the other miniDP instead of the DP ? Any other ideas on how to get it working ?

Thanks
 
My guess is that an RX 580 is more likely to support MST correctly in macOS given it's use in the latest 27" 5K iMacs.
I know, not that helpful but it may be your only route.
 
From my personal observations I'd guess that Nvidia GPUs only support 5K when using the Dell UP2715K.
 
Thank you all for the answers.

Fl0r!an said:
From my personal observations I'd guess that Nvidia GPUs only support 5K when using the Dell UP2715K.
Click to expand...

I installed Bootcamp (which was a little bit painful) and booted in Windows 8. Once Nvidia Drivers and HP display drivers were installed in Windows, the display worked without any issue in 5K and without fumbling with the cables. So I guess the issue is not the GTX 1080 hardware itself.

But still not working when rebooting under MacOS. Since the Z27q is supported by Apple, I guess the only remaining issue is in the Nvidia drivers. I'll try to report that bug to NVidia to see if a correction can be expected in the future...

Once in MacOs after the Windows experiment, I chose mirroring between the 2 instances of the display, and Optimise for the second one (the one not showed). The display is almost stable (much more than during my first attempt), with 2 partial duplicate desktops of 2560x2880 and a full one : IMG_8335.jpg

The screen OSD correctly reports the right 5K@60Hz resolution. but there is a strange ghosting effect..
Maybe I could achieve something using SwitchResX?

The horrible flickering effect came back when unplugging the second DP cable. I guess it will be reset once I boot in Windows...
 
ArleX said:
I installed Bootcamp (which was a little bit painful) and booted in Windows 8. Once Nvidia Drivers and HP display drivers were installed in Windows, the display worked without any issue in 5K and without fumbling with the cables. So I guess the issue is not the GTX 1080 hardware itself.

But still not working when rebooting under MacOS. Since the Z27q is supported by Apple, I guess the only remaining issue is in the Nvidia drivers. I'll try to report that bug to NVidia to see if a correction can be expected in the future...
Click to expand...
Yes, I wasn't precise enough. I wasn't talking about the hardware, but about macOS drivers.
 
ArleX said:
Thank you all for the answers.



I installed Bootcamp (which was a little bit painful) and booted in Windows 8. Once Nvidia Drivers and HP display drivers were installed in Windows, the display worked without any issue in 5K and without fumbling with the cables. So I guess the issue is not the GTX 1080 hardware itself.

But still not working when rebooting under MacOS. Since the Z27q is supported by Apple, I guess the only remaining issue is in the Nvidia drivers. I'll try to report that bug to NVidia to see if a correction can be expected in the future...

Once in MacOs after the Windows experiment, I chose mirroring between the 2 instances of the display, and Optimise for the second one (the one not showed). The display is almost stable (much more than during my first attempt), with 2 partial duplicate desktops of 2560x2880 and a full one : View attachment 707558

The screen OSD correctly reports the right 5K@60Hz resolution. but there is a strange ghosting effect..
Maybe I could achieve something using SwitchResX?

The horrible flickering effect came back when unplugging the second DP cable. I guess it will be reset once I boot in Windows...
Click to expand...
If you can, try and get your hands on an RX580, or even an RX560, as that is far more likely to work for you. Just ensure you're using 10.12.6 or High Sierra.
 
Most likely you have to use a little work around as your MP will not boot in 5K. (like the Dell)
You should be able to boot in 4K and than manually set it to 5K.
My friend couldn't get it to work under Sierra, he uses EC.
 
I don't think you got it!
The Dell isn't working 'fine'!!

You need this workaround to get 5K, knowing this, I urge you (the TS) to try the same workaround with the HP.
I don't know of anybody using this HP.
 
Last edited:
carpsafari said:
I don't think you got it!
The Dell isn't working 'fine'!!

You need this workaround to get 5K, knowing this, I urge you to try the same workaround with the HP.
I don't know of anybody using this HP.
Click to expand...

Sorry if that reply was for me I am not the original poster. I'm new to this thread, I'm not using any 5k monitors I was just asking out of curiosity.
 
There are some threads on this topic at tmx86. I don't think anyone managed to get the HP 5K working with a Nvidia GPU in macOS using the same methods which work for the Dell 5K.
 
carpsafari said:
I don't think you got it!
The Dell isn't working 'fine'!!

You need this workaround to get 5K, knowing this, I urge you (the TS) to try the same workaround with the HP.
I don't know of anybody using this HP.
Click to expand...

I would gladly try but since I have a Pascal GPU I am stuck in Sierra...

I might try a used RX580 once they become available second hand and others have experimented.

In the meantime, I just use it in 4K.
 
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