Scaling 1440p in a 4k monitor compare with NATIVE 1440p monitor?

[Little Jim]

Hi guys,
I'm looking to get a suitable external monitor for my MacBook Pro 15' 2019. I m thinking to 2 option: first is my favor the LG Ultrafine 4k 24inch, second is a 24-25 inch at 2560-1440 resolution (there are plenty of those in the market).
After doing some research, I found that if using the Ultrafine 4k, most people will have to scaled it down to "2560-1440" to make the text bigger enough for using. Hence I think, why don't just get a native 2560-1440 resolution (which why the second option get in, and it also save a lot money compare with my favor option).
Could you guys give me some knowledge?
-At scaled 2560-1440, does the Ultrafine 4k perform better than a native 2560-1440? Or it is the same? I m just ask in term of pixels, not in term of color (since I believe the Ultrafine will outperform most of average rivals).
-Does a 4k monitor that forced to scaled 2560-1440 have ANY superior than a 2560-1440 monitor scaled native 2560-1440 on macOs?
Thank you guys

 

[joevt]

-At scaled 2560-1440, does the Ultrafine 4k perform better than a native 2560-1440? Or it is the same? I m just ask in term of pixels, not in term of color (since I believe the Ultrafine will outperform most of average rivals).

I don't think anyone's measured the performance difference between the three options probably because no-one has noticed a difference.
1) outputting 1440p (let the display scale it to 4K)
2) scaling up low res 1440p to 4K
3) scaling down 1440p HiDPI (5K) to 4K

Of course, gaming will be much faster for #1, maybe slower for #2 (maybe only slightly, if at all), and slowest for #3 but most other types of apps will be the same.

-Does a 4k monitor that forced to scaled 2560-1440 have ANY superior than a 2560-1440 monitor scaled native 2560-1440 on macOs?

Option #3 with the HiDPI mode will have better looking text because it is scaling 5K down to 4K in a "Looks like 1440p" mode.

You probably won't see a difference between #1 and #2 for a 4K display.

On my Apple 30" Cinema Display, scaling 800p to 1600p using the GPU (as in option #2) adds some kind of smoothing. Scaling 800p to 1600p using the display (as in option #1) has no smoothing - the same color for a pixel in the 800p framebuffer is used for four pixels of the 1600p display so it looks blocky. Some displays use a different method to scale up.

 

[Stephen.R]

The GPU load to drive a 2560x1440 24" display is probably lower than the GPU load to run a 4K display at any resolution.

But more specifically, the GPU load to run a 24" 2560x1440 display is going to be significantly lower than running a 4K display at "looks like 2560x1440" because to do that, macOS is rendering a 5K frame buffer, then downscaling it to 4K.

However, the result will look better, due to a much higher PPI, and as you're using a 15" MBP, it's got a dedicated GPU, which is going to be always be active for any display, so you shouldn't have any performance issues using a scaled Hi-DPI resolution.

Of note: I don't know how common it is to use 2560x1440 on a 24" 4k display. A 27" 4K? Sure. People want it to look "the same" as the 5K iMac or 5K Ultrafine, but have a 4K display. On a 24", I think things would be a bit small. Personally I find 2304x1296 "perfect" for 24". However this is the beauty of getting a hi-dpi display (e.g. 4k, 5k, etc): you can scale the visual resolution to what works for you (within reason).

 

[ght56]

I use a 4K 27-inch and QHD 25-inch UltraSharp side by side each day that's in the identical product family. Yes, there is a difference provided you are not using the 4K display in a low resolution mode. I find it is most pronounced with serif fonts, dark mode, and most especially small text, where the 4K is notably more crisp. The QHD is by no means unsatisfactory...however, if looking at a massive spreadsheet that is zoomed out to look super tiny, I'll view it on one of the 4Ks as there is a pretty big difference.

If you are using the 4K in a 'low resolution mode', it more or less looks like the QHD display, and it is still placing a bigger tax on the GPU than just using a native QHD display.

 

[kepler20b]

Hi guys,
I'm looking to get a suitable external monitor for my MacBook Pro 15' 2019. I m thinking to 2 option: first is my favor the LG Ultrafine 4k 24inch, second is a 24-25 inch at 2560-1440 resolution (there are plenty of those in the market).
After doing some research, I found that if using the Ultrafine 4k, most people will have to scaled it down to "2560-1440" to make the text bigger enough for using. Hence I think, why don't just get a native 2560-1440 resolution (which why the second option get in, and it also save a lot money compare with my favor option).
Could you guys give me some knowledge?
-At scaled 2560-1440, does the Ultrafine 4k perform better than a native 2560-1440? Or it is the same? I m just ask in term of pixels, not in term of color (since I believe the Ultrafine will outperform most of average rivals).
-Does a 4k monitor that forced to scaled 2560-1440 have ANY superior than a 2560-1440 monitor scaled native 2560-1440 on macOs?
Thank you guys

yes. most people that use 5k or 4k monitors for office applications actually are displaying in scaled resolutions.

the primary benefit is the fidelity and clarity of the text and videos/games.

if you're not sure and haven't seen the difference you should walk into a store and be able to see the actual clarity difference between a 27" monitor that is native 2560x 1440 and a 27" 4k monitor that is displaying 2560x 1440. the difference IMO would be noticeable as far as 6feet from the screen.