16 M1 Max & 27" 5k Choppy Graphics

[mrpndev]

Just got my 24 core M1 Max. When running in clamshell mode with the display plugged in, the graphics are very choppy. Expose and even cursor movement is pretty bad.

Any idea what can be causing it? It feels it runs at maybe 20fps. Disappointing considering that my 2017 MBP was able to run this display without issues.

 

[Christopher Kim]

I'm assuming this is the LG 27" 5K Ultrafine monitor? How do you have it connected to your new 16" MBP, is it directly via a Thunderbolt 3 cable? Or are you going through any hub of any sort?

Also, assume you're running at the default "Looks like 2560 x 1440" HiDPI resolution?

If you just got your 16" MBP, I'd update to the latest Monterey 12.1 as well (it shipped with an early 12.0 release before the official Monterey was released, which they named 12.0.1). Also in the first day or two, new MBPs take a lot of resources indexing / spotlight uses up lots of resources - still feels unlikely that would cause that level of stuttering though if everything else is standard. Definitely something seems wrong.

 

[mrpndev]

I should've clarified:

Yes, it's the 27" LG 5k display. It's connected via TB3 directly. Resolution is set to 2880x1620. MBP is updated to 12.1 and I've had it for about a week now.

 

[Christopher Kim]

Hmm, that is odd... Even though you're running it at a non-integer scale of 2880x1620 (which takes more GPU usage), the laptop should be more than powerful enough to do that without any choppiness... just for troubleshooting, if you change your display resolution to the perfect pixel-doubled "Looks like 2560x1440", is it still choppy? Or does it smoothen out?

 

[Anonymous Freak]

And in what manner is it "choppy"? Dragging a window in Finder with no applications open, or trying to play a graphics-intensive 3D game at full resolution?

Because my M1 (non-Pro/Max) Mac Mini can run two 4K displays at non-integer scale and is silky smooth at nearly everything except 3D gaming. And even 3D gaming is still "pretty darn good."

 

[mrpndev]

Hmm, that is odd... Even though you're running it at a non-integer scale of 2880x1620 (which takes more GPU usage), the laptop should be more than powerful enough to do that without any choppiness... just for troubleshooting, if you change your display resolution to the perfect pixel-doubled "Looks like 2560x1440", is it still choppy? Or does it smoothen out?

Perhaps very little. Nothing significant.

And in what manner is it "choppy"? Dragging a window in Finder with no applications open, or trying to play a graphics-intensive 3D game at full resolution?

Because my M1 (non-Pro/Max) Mac Mini can run two 4K displays at non-integer scale and is silky smooth at nearly everything except 3D gaming. And even 3D gaming is still "pretty darn good."

For instance Firefox window being dragged around, or Expose moving a bunch of windows.

If it's an issue, I feel that it is software related. Either that, or I got used to the 120Hz ProMotion laptop display and now the 5k just looks bad, lol.

 

[WilliamG]

I have the same setup - no issues. You're probably just used to 120hz.

 

[Patcell]

If you to to “About This Mac” and select “System Report” and go to graphics/ displays, does it say the LG UltraFine is running at 60hz?

 

[Fastball32]

I am running one LG 5K and two LG 4K 21.5" simultaneously with no issues on my 16" Max. If the cursor is choppy, consider bluetooth as sometimes that occurs with the original m1 macbooks.

 

[Fastball32]

Also forgot to mention that I was running it in clamshell mode for the triple monitors connected wirelessly to an Apple Trackpad, MX3 mouse, and Apple keyboard with no issues.

 

[Christopher Kim]

If it's an issue, I feel that it is software related. Either that, or I got used to the 120Hz ProMotion laptop display and now the 5k just looks bad, lol.

I have the same setup - no issues. You're probably just used to 120hz.

Haha - guess that could be true. Could see that happening - like when using Pro Motion on the iPad Pros or the iPhone 13 Pros, when I first "upgraded", while I could notice the difference, it wasn't massive. I noticed it and liked it and appreciated it, but it didn't blow me away. But after you're used to it, when you get it taken away, that's when you really notice it. More than it was in the other direction!

 

[mrpndev]

If you to to “About This Mac” and select “System Report” and go to graphics/ displays, does it say the LG UltraFine is running at 60hz?

It does indeed run at 60Hz. I guess it's some UI choppiness and me not being used to 60Hz anymore after using the laptop itself for a few days.

 

[Patcell]

It does indeed run at 60Hz. I guess it's some UI choppiness and me not being used to 60Hz anymore after using the laptop itself for a few days.

Interesting. Yeah, it could be your mind playing tricks in you. Your computer should not have any issue driving the 5K display smoothly, even at scaled resolutions.

I have a 14” M1 Pro that has no problem ringing two 4K displays plus the internal smoothly. And my external displays are set to “UI looks like 2560x1440” meaning it is rendering both displays at 5K and down sampling to 4K.