I found myself posting this information so frequently on forum threads and in video comments that I wanted to put it all together in one place so that I can share my experience and what I’ve learned with a single link. And, while this is primarily a vintage computing blog, not every post is of that nature. Apologies to my retro-only readers. (Well, there is an Amiga and a Lisa in that second photo down the page, there, so…)
I recently replaced my aging 2017 5K Retina iMac with a Mac Studio, powered by an M1 Max processor and 32GB of RAM. Some months earlier I upgraded my aging laptop to a 2022 M2 MacBook Air. That iMac’s beautiful 27-inch, 5K retina display was hard to part with, and so I wanted to give the new desktop system a very nice screen. And I have, in the form of an LG DualUp 28-inch display.
It’s an unusual display; it is a 16:18 aspect panel with a native resolution of 2560×2880. It is “tall” in its normal orientation, but I’ve chosen to use it rotated which makes it look rather square (a great orientation for this display). A perfect screen for my use cases as a general UNIX system and web development workstation. (I do not game on my desktop Mac nor do I watch feature films, so a more traditional 16:9 aspect ration has little value to me here.) I’ve had this system up and running for two months now and I can say that, of all the displays I’ve ever used, this one is my favorite.
Doing research to spec out the screen for this iMac replacement, I encountered a large number of people lamenting the use of 4K displays with Macs, noting that the Apple 5K displays, with a 218 pixel/inch density, allow for a computationally easy halving of the native display resolution to achieve an ideal desktop rendering. A 5K Apple display has a native resolution of 5120×2880 and the default view mode is a “looks like” 2560×1440 desktop — razor sharp. Halving the native display resolution is easy peasy for GPU hardware — a small lift. This is, presumably, why Apple’s Retina displays are 5K rather than 4K. The thing with 4K displays is that in their typical native 3840×2160 resolution, they present the UI elements far too small, while the system-suggested half-resolution rendering is a sharp “looks like” 1920×1080 display where the UI elements appear too large — there’s too little desktop real estate.
The way around this is to have macOS “scale” the display to a more ideal lower resolution, but choosing that option in display preferences presents a warning: “Using a scaled resolution may affect performance.” What the OS does here is to scale up the chosen resolution to double height and double width (4x the pixels displayed) and then scale them back down to the display’s native resolution — 60 times per second. Indeed, this can be too much for certain older systems out there. But, as you will see, modern Macs should be able to handle the task just fine.Continue reading