Dell UP2715K screen tearing

[SamPotts]

I've been on a mission to get this screen working on my 4,1 Mac Pro. First I tried the 7970, no dice, then bought a K1200, which I think would have worked had I added the `nv_spanpolicy` boot arg, but I forgot. Then I bit the bullet and bought a GTX970, set the boot args and the 5K screen came to life but all was not well. Firstly the screen seems to have a yellow tint at the top and I'm getting screen tearing on anything that has to redraw a large percentage of the screen (e.g. a modal window on a website with a backdrop). Anyone else getting this? I thought the iMac 5K GPU was meant to be under-specced but I must say, never seen any graphical issues in day to day use.

 

[ActionableMango]

Sounds like it is not accelerated. Which boot arg did you set? One of them is to disable the Nvidia drivers, which could cause this problem. Make sure you've reenabled the Nvidia drivers after you've installed the web drivers.

The other problem I've read about here is that it's only with Safari. I.E. you are doing everything right, but there is a Safari bug and if you use another browser, it's fine.

 

[SamPotts]

Definitely odd. I ran this:

sudo nvram boot-args="nvda_drv=1 nv_spanmodepolicy=1"

Should it be this instead?

sudo nvram boot-args="kext-dev-mode=1 nv_spanmodepolicy=1"

I was confused by the comments on this page:
http://www.macvidcards.com/blog/the-5k-report

 

[leadfeet]

https://forums.macrumors.com/posts/22142578/

 

[ActionableMango]

Oh, I was thinking of the Maxwell driver update boot args, not the 5K boot args. No, I don't think it's the boot args now.

 

[SamPotts]

https://forums.macrumors.com/posts/22142578/

Thanks for that but this is a 5K screen and that thread seems to be about different issues

 

[SamPotts]

Oh, I was thinking of the Maxwell driver update boot args, not the 5K boot args. No, I don't think it's the boot args now.

No worries, thanks for your help!