Wednesday, May 27, 2020

The LG UltraFine 5K, kernel_task, and Me

Peter Steinberger:

Since we first purchased the displays, we’ve been having issues with them, starting with delayed shipping, ghosting, and Wi-Fi interference, and moving on to compatibility — there’s no HDMI, DisplayPort, or similar. The only way to use these monitors is with a modern Mac. As for the compatibility issue, that was a known tradeoff, and for me, it was acceptable. After all, the benefit of only having a single cable as a modern docking station and a beautiful panel outweighed the drawbacks. I still remember my innocent excitement.

Since receiving these displays, we’ve had to return most of them to get fixes for various issues, and we’ve patiently updated the firmware multiple times with LG’s crappy Screen Manager software. There are also issues with expanding batteries, and Apple has blamed the LG 5K, saying just don’t use it a lot and you’ll be fine.


The 16-inch MacBook Pro doesn’t seem to suffer from this temperature sensor misplacement and can drive the LG UltraFine without slowdown on both ends. […] The bad news: The LG can provide 87 watts of power, but the notebook comes with a 96-watt adaptor. This means that the battery is constantly compensating. […] I mostly use the separate power plug to fix the “missing 9-watt problem.”

Despite all this, he recommends it. There just aren’t many Retina options.


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I replaced at 2015 27" iMac with an updated Mac Mini. I don't really want a Mini, but Apple doesn't sell a reasonably priced tower. I had to ditch the iMac because the display had terrible ghosting (which started just out of the AppleCare lifetime) that I could no longer ignore.

The LG Ultrafine was the only 5K option I could find. I was put off by the lack of ports, but mostly I didn't want to place my trust in the same LG panel. I ended up getting a 4K display from HP that has HDMI, Display Port, Mini Display Port, and HDMI. I'm running it at a scaled resolution that's equivalent to the 5K display, and you know what? It looks amazing. If I look side by side and really strain, I can see the actual 5K is sharper, but it's barely noticeable and certainly not worth spending that much money on an LG display that has serious defects.

Fred, what HP monitor are you using? I have a 2018 mini which works great but the 27” ASUS 4K panel have is just OK. Would be interested in trying your solution. Never even considered the LG because cost+bugs.

HP Z27 -

I've had it for about a year now and it's been great. It's also such a relief to have a separate display after living the iMac life for a few years. It's just a delight to plug in a laptop or a Nintendo Switch when I want.

>There are also issues with expanding batteries, and Apple
>has blamed the LG 5K, saying just don’t use it a lot and
>you’ll be fine.

That's actually interesting. They're blaming the bloated batteries on low cycle count, which matches my own experience. I have my Macs almost always plugged in, and I've had bloated batteries on every single MacBook I've owned during the last decade.

> The only way to use these monitors is with a modern Mac

You should be able to connect it to a PC with a Thunderbolt AIC and/or a modern motherboard.

Been using it since the release together with an MBP that was released the same year. Of all issues I only encountered kernel panics which practically disappeared around 10.14.5. Moreover I have an external HDD enclosure connected over USB-C (for backups) and it works just fine, including whenever I re-plug my laptop.

The most annoying of it is the way macOS behaves when an external display is plugged or unplugged. Flickering is infuriating.

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