6 ms·

The performance depends very greatly on the resolution you run the 4K screen at. If you're using a non-evenly scaled resolution (i.e. not exactly 1x or 2x rend

The performance depends very greatly on the resolution you run the 4K screen at. If you're using a non-evenly scaled resolution (i.e. not exactly 1x or 2x rendering) it's not gonna be fantastic. Running at 'default' 2x my 2018 runs 2x 24" 4Ks without issue - the problem most people have I think is that they buy much larger displays and then want to use a higher rendered resolution, which is where the iGPU will struggle.

larrik 7y ago
Isn't "4K" the resolution??
- gambiting 7y ago
  Yes, but I guess just like I don't know anyone who runs their retina macbook at the native resolution, you don't need to run a 4K screen at 4K. For instance 1080p gives you perfect 2x2 scaling with no blurriness at all since every pixel perfectly translates into 4. I have no idea why you'd do that, but I can see why that's a valid consideration for some people.
- zaphoyd 7y ago
  Macs have the option to run a 4K screen at different "effective dpis" via scaling. The default ~200% scaling factor gives you a 1920x1080 work area that is twice as sharp. A lot of folks (myself included) choose to draw larger work surfaces (I use a 5120x2880 canvas with 2560x1440 work area on my 24 inch 4Ks). A 4K screen is high enough DPI that when scaled text still looks very nice (nicer than a native res 1440p display). Doing this (especially on multiple displays) requires a lot of GPU power.
- bzzzt 7y ago
  Yes, but since you can get 4k on everything from 24" to 84" you'll want to choose between more space or bigger fonts depending on the setting. macOS can do 'fractional scaling' when the integer scaling isn't to your preference, but the implementation works by rendering to a much higher resolution internally and then scaling down which needs a beefy GPU to run without noticeably overhead.
  - bluedino 7y ago
    Anything bigger than 24" or so and the blurriness gets bad. The pixel density just isn't quite there.
    - larrik 7y ago
      Depends how close you are to it, though, I would think
    - FpUser 7y ago
      I am reading this on 32" 4K monitor (2 of them actually are hooked to a gaming laptop). I do not notice any blurriness.
      - bluedino 7y ago
        Are you running a non-default resolution?
        FpUser 7y ago
        I am running those at native 4K resolution. Frankly I do not get a point of buying 4K monitor to run it at lower resolution
      - FpUser 7y ago
        Yep this definitely deserves downvote. I guess 4K must be blurry by definition
- stephenr 7y ago
  As others have said it is the physical resolution, which is why the term used in macOS is "Looks like X by Y". The default of "looks like 1920x1080" is straight "@2x" - so the rendering is pixel doubled in both axis, giving a crisper image than a same size "real" 1920x1080 display.
CrazyStat 7y ago
> the problem most people have I think is that they buy much larger displays and then want to use a higher rendered resolution I'm not going to buy a 4k screen with the intention of running it at 1080p. There are plenty of large 1080p screens out there. If I buy a 4k screen it's because I want to run it at 4k.
- joosters 7y ago
  I'm using a 4k display on a mac mini, but I've got it set halfway between the 'larger text' (1080p x2) and 'more space' (4k with no pixel doubling). This doesn't mean I'm running it at a lower resolution - behind the scenes, the mac is actually rendering the display at 6016x3384 and then smoothly scaling it down to the native 4k of 3840x2160. Because it's having to draw everything at a higher resolution than the actual screen, performance does take a hit, but I find everything still works perfectly smoothly and responsive (just don't try playing games at this resolution on the mac mini!)
  - joshmn 7y ago
    Mac Mini user here also: What display are you using?
    - joosters 7y ago
      It's a BenQ EW3270U, 4k @ 60hz, connected via USB-C. It's been working just fine, I'd recommend it. I have a second monitor which is not high-DPI but 2560x1440, connected with a USB-C => displayport cable. Surprisingly, the mix of high-DPI and normal DPI monitors works really well, with no problems, even when moving windows from one display to the other.
- stephenr 7y ago
  ... I think you've missed the point. It isn't running at 1080p. It's doing "@2x" pixel rendering (commonly called "Retina") - so it uses 4 physical pixels to render one "screen" pixel, giving you much crisper.. everything.
Lightbody 7y ago
Just chiming in here and endorsing the eGPU add-on to resolve 4k monitor performance for non-standard resolutions / pixel density. Without it things get pretty chunky. With it, smooth as butter.

larrik 7y ago

Isn't "4K" the resolution??

gambiting 7y ago
Yes, but I guess just like I don't know anyone who runs their retina macbook at the native resolution, you don't need to run a 4K screen at 4K. For instance 1080p gives you perfect 2x2 scaling with no blurriness at all since every pixel perfectly translates into 4. I have no idea why you'd do that, but I can see why that's a valid consideration for some people.
zaphoyd 7y ago
Macs have the option to run a 4K screen at different "effective dpis" via scaling. The default ~200% scaling factor gives you a 1920x1080 work area that is twice as sharp. A lot of folks (myself included) choose to draw larger work surfaces (I use a 5120x2880 canvas with 2560x1440 work area on my 24 inch 4Ks). A 4K screen is high enough DPI that when scaled text still looks very nice (nicer than a native res 1440p display). Doing this (especially on multiple displays) requires a lot of GPU power.
bzzzt 7y ago
Yes, but since you can get 4k on everything from 24" to 84" you'll want to choose between more space or bigger fonts depending on the setting. macOS can do 'fractional scaling' when the integer scaling isn't to your preference, but the implementation works by rendering to a much higher resolution internally and then scaling down which needs a beefy GPU to run without noticeably overhead.
- bluedino 7y ago
  Anything bigger than 24" or so and the blurriness gets bad. The pixel density just isn't quite there.
  - larrik 7y ago
    Depends how close you are to it, though, I would think
  - FpUser 7y ago
    I am reading this on 32" 4K monitor (2 of them actually are hooked to a gaming laptop). I do not notice any blurriness.
    - bluedino 7y ago
      Are you running a non-default resolution?
      - FpUser 7y ago
        I am running those at native 4K resolution. Frankly I do not get a point of buying 4K monitor to run it at lower resolution
    - FpUser 7y ago
      Yep this definitely deserves downvote. I guess 4K must be blurry by definition
stephenr 7y ago
As others have said it is the physical resolution, which is why the term used in macOS is "Looks like X by Y". The default of "looks like 1920x1080" is straight "@2x" - so the rendering is pixel doubled in both axis, giving a crisper image than a same size "real" 1920x1080 display.

CrazyStat 7y ago

> the problem most people have I think is that they buy much larger displays and then want to use a higher rendered resolution I'm not going to buy a 4k screen with the intention of running it at 1080p. There are plenty of large 1080p screens out there. If I buy a 4k screen it's because I want to run it at 4k.

joosters 7y ago
I'm using a 4k display on a mac mini, but I've got it set halfway between the 'larger text' (1080p x2) and 'more space' (4k with no pixel doubling). This doesn't mean I'm running it at a lower resolution - behind the scenes, the mac is actually rendering the display at 6016x3384 and then smoothly scaling it down to the native 4k of 3840x2160. Because it's having to draw everything at a higher resolution than the actual screen, performance does take a hit, but I find everything still works perfectly smoothly and responsive (just don't try playing games at this resolution on the mac mini!)
- joshmn 7y ago
  Mac Mini user here also: What display are you using?
  - joosters 7y ago
    It's a BenQ EW3270U, 4k @ 60hz, connected via USB-C. It's been working just fine, I'd recommend it. I have a second monitor which is not high-DPI but 2560x1440, connected with a USB-C => displayport cable. Surprisingly, the mix of high-DPI and normal DPI monitors works really well, with no problems, even when moving windows from one display to the other.
stephenr 7y ago
... I think you've missed the point. It isn't running at 1080p. It's doing "@2x" pixel rendering (commonly called "Retina") - so it uses 4 physical pixels to render one "screen" pixel, giving you much crisper.. everything.

Lightbody 7y ago

Just chiming in here and endorsing the eGPU add-on to resolve 4k monitor performance for non-standard resolutions / pixel density. Without it things get pretty chunky. With it, smooth as butter.