Mac mini M1 + LG Ultrafine 5K = Non-smooth experience

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Level 1

8 points

Mac mini M1 + LG Ultrafine 5K = Non-smooth experience

Hello,

For a week now, I have a Mac mini M1 (16GB DDR and 512GB SSD) that I connected to an LG Ultrafine 5K screen.

I first had Bluetooth problems, my keyboard (Magic Keyboard) and my mouse (Magic Mouse 2) were both victims of kind of lag. I was told to update macOS, it was already 11.2.3. I finally fixed the problem by disabling the Mac mini's Wifi. Okay.

The second problem, and the one that I can't seem to solve, is that I find the overall experience lacking in fluidity, it's quite difficult to describe but the change with my 2013 iMac is obvious. The performance is (by far) much better on the Mac mini (Exporting in Final Cut) but the experience is not, for example, the scrolling in a web page seems less smooth, the movement of the mouse also, things as simple as that. It always feels like there's a little latent there, as if the screen lacked responsiveness, while my iMac seemed to respond instantly.

I asked myself and did some testing, but I can't figure out where the problem may be coming from. I tried to turn off Bluetooth and switch to wired, no improvement. I checked the framerate of the screen, it oscillates between 30 and 60 fps, like my old iMac so i guess it's ok. I've read that there are several types of Thunderbolt cable with different bit rates, do you think changing the Thunderbolt cable that connects the screen to the Mac mini might make things better?

Thanks for your help!

Edit:

After performing some tests by changing the screen resolution, I noticed that by activating the resolutions marked "low resolution" in the list of system preferences of macOS (for example "2560x1440 (low resolution)") or at On the contrary, when I activate the maximum resolution of the 5120x2880 screen, the result is obvious, it is much smoother, mouse movements are precise, like my old iMac. These two resolutions do not use retina, should I conclude that it is a problem of "retina management" by my Mac mini?

Mac mini 2018 or later

Posted on Apr 26, 2021 1:39 AM

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Answer 1

May 27, 2021 11:51 AM in response to aiacciu

When the Mac Mini (M1) came out earlier this year, I bought it. And because Apple sells a branded LG monitor they helped design, in two sizes, I bought both with the expectation that I could use the Thunderbolt connections from the Mac Mini and drive both the 5K monitor and the 4K monitor with Apple's new, powerful computer. I was wrong. It took a phone call to Apple Support to find out you cannot connect both of those at the same time via Thunderbolt to the Mac Mini. When I did, only one worked.

In the end, I kept the 5K and returned the 4K monitor. I like having two screens, but I didn't want to fuss with it any longer. There may be a way to use other LG monitors connected differently to the Mac Mini, and make it work. I don't have the time to waste.

Unfortunately, the problem didn't end there: the Mac Mini apparently has a software issue with resolution settings the affect the Apple-branded LG monitors I've owned. I tested the Mac Mini on both, and the problem was a recurring one: pixel shifts down the middle of the screen. Future software updates of the Mac OS did not correct the problem.

I've owned Apple's flagship computer and monitor, the Mac Pro + its XDR 6K Cinema display: the two will cost you $12,000. I connected the Mac Mini to the XDR, and it yielded a perfect image every time, with no pixel shifts. I also followed LG's advice to determine whether or not the pixel-shifting was a software issue from Apple, or whether it was the LG monitor. As a result, I isolated the problem and came to the inescapable conclusion that it was a software or hardware issue with the Mac Mini. I was hoping the problems would just go away (ha ha), and they didn't. I recently wrote to Apple, in a two-page letter, and they never responded.

If I were you, I'd return the current Mac Mini (M1) and wait for the newer version coming out later this year, according to Macrumors.com. I'm always wary when I buy the first version of any computer, and in the past, I've never had a problem with an Apple computer ... until now. I've been buying computers since the seventies, including dozens of Apple computers.

The Mac Mini is the only one that's ever failed me. I've recently bought the new iMac M1 for my wife, and she loves it. So far, it looks like a great product. I'll be buying another one shortly, for myself. Apple can obviously make a great product, but like so many other companies these days, after-sales support is, in my experience, inconsistent.

My Mac Mini M1 is getting the boot: I run a small business and I can't afford to have a computer with an exasperating, unresolved problem that makes it difficult for me to get my work done: I write books, and I can't read text that's jagged, crooked, and out of alignment because of pixel shifting. I used to tell everyone to get an Apple computer because "they just work." Well, most of the time... Your mileage with the Mac Mini M1 may vary.

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Answer 2

hcsitas

Level 6

13,970 points

Apr 26, 2021 6:31 AM in response to aiacciu

I see. I agree it sounds like a bug. IMO you should open a case with Apple directly https://support.apple.com/en-us/HT201232

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Answer 3

aiacciu Author

Level 1

8 points

Apr 26, 2021 6:28 AM in response to hcsitas

Using 5K resolution on this screen doesn't really make sense, everything is too small. The goal of this screen is to use the 2560x1440 resolution in retina mode (default and native resolution for this screen), to take advantage of the high pixel density (218 ppi). And it is precisely this resolution that is problematic.

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Answer 4

hcsitas

Level 6

13,970 points

Apr 26, 2021 6:47 AM in response to aiacciu

Doesn’t look like the cable. If the firmware needs updating, nothing to think about, jdi. I doubt very much replacing the mini will help, plus you’ll run out of your return window. A tough situation! Good luck!

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Answer 5

hcsitas

Level 6

13,970 points

Apr 26, 2021 4:33 AM in response to aiacciu

You’re still within the return window, so you might want to consider the new 4.5K Retina iMac, available for order starting this Friday.

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Answer 6

aiacciu Author

Level 1

8 points

Apr 26, 2021 6:41 AM in response to hcsitas

Thank you for your answer. This is what I did, they told me they never encountered this problem and asked me to re-install macOS. I did it, unfortunately, it didn't change anything. I'm thinking of trying to update the display's firmware, get a faster Thunderbold cable (I'm currently using the cable that came with the display) and if that still doesn't solve the problem, I'll send the hardware back.

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