27 inch imac with dual 4k monitor setup vs 5k

bodhisattva1123

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Ok so I've searched for about a week and can't seem to find anyone who can give me a straight answer so I signed up here because guys have helped me out here in the past...ok so multi part question as short as possible, I've got a 2019 27 inch 5k imac. I'm looking to set up 2 additional 27 inch monitors on the left and right. Apparently I can't do two 5k monitors unless I get the imac pro? Is there any work around to this and if so how? If not, how do I set up dual 4k monitors with a 5k imac? And will it show a disparity between the 5k imac and 4k monitors. Thanks in advance!
 

phpmaven

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Ok so I've searched for about a week and can't seem to find anyone who can give me a straight answer so I signed up here because guys have helped me out here in the past...ok so multi part question as short as possible, I've got a 2019 27 inch 5k imac. I'm looking to set up 2 additional 27 inch monitors on the left and right. Apparently I can't do two 5k monitors unless I get the imac pro? Is there any work around to this and if so how? If not, how do I set up dual 4k monitors with a 5k imac? And will it show a disparity between the 5k imac and 4k monitors. Thanks in advance!
https://apple.stackexchange.com/questions/181330/how-many-external-monitors-does-the-imac-27-with-5k-display-support
 

AlexJoda

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Apr 8, 2015
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Because 27" 4K displays have a weird magnification factor compared to the 5K display I am using 27" 1440p displays (Lenovo P27H with USB-C/Display port connectors for a 1:1 USB-C connection to the iMac) on my 5K iMac. They have the same size and resolution in Points as the 5K, a thin frame and a really good picture even compared to the 5K. If I have something really critical I move it to the 5K....
 
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bodhisattva1123

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Because 27" 4K displays have a weird magnification factor compared to the 5K display I am using 27" 1440p displays (Lenovo P27H with USB-C/Display port connectors for a 1:1 USB-C connection to the iMac) on my 5K iMac. They have the same size and resolution in Points as the 5K, a thin frame and a really good picture even compared to the 5K. If I have something really critical I move it to the 5K....
Thank you for the info. Is your monitor the P27H-10? Or is it a P27H? First I'm hearing about this monitor, I like the way they look next to an imac but I'm not sure I'm looking at the right one.
 

theluggage

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Jul 29, 2011
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And will it show a disparity between the 5k imac and 4k monitors.
Because 27" 4K displays have a weird magnification factor compared to the 5K display
A 4k display in "looks like 2560x1440" scaled mode gives you the same UI size as 5k in default resolution and is significantly better quality than a native 1440p display, because it isn't 1440p - it is 5k downsampled to 4k, which includes substantially more detail than 1440p would. Frankly, although it is slightly "softer" than a 5k display, it isn't night and day sharper. My 0.5c worth: if your workflow doesn't involve climbing up on the desk with a jeweller's loupe and doing A/B comparisons between the 4k scaled and 5k, you won't notice.

What you will notice is colour differences between the iMac's P3 display and a standard-gamut 4k. You can reduce that with calibration but, at the end of the day, a wide-gamut display can reproduce colours that a standard gamut can't.

The extra GPU load might cause lag on a Mac Mini or lower-end MacBook with with a relatively feeble iGPU, but The 5k iMacs all have half-decent GPUs and dedicated VRAM.

If you've seen the (awful) result of (say) scaling 1440p to 1080p on a 'non-retina' display, try and put that out of your head - MacOS scaling on "retina" class displays is in a different league.

Plus, it only takes a jiffy to switch it to either 1:1 4k resolution or pixel-doubled "looks like 1080p" mode to get unqualified 4k resolution when you need it. The main reason for using scaled mode is to get the size of system fonts, menus and dialogs "just right" - if you're displaying a full-screen image or even a window full of text that doesn't matter much - virtually every application lets you choose the magnification used for 'content'.

That said, going for 1440p secondary display(s) is a perfectly sensible way of saving a few hundred bucks c.f. buying (possibly two) 4k displays, given that you're mostly going to be focussing in the primary 5k, but I don't think you can justify it on "quality" grounds.
 
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bodhisattva1123

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A 4k display in "looks like 2560x1440" scaled mode gives you the same UI size as 5k in default resolution and is significantly better quality than a native 1440p display, because it isn't 1440p - it is 5k downsampled to 4k, which includes substantially more detail than 1440p would. Frankly, although it is slightly "softer" than a 5k display, it isn't night and day sharper. My 0.5c worth: if your workflow doesn't involve climbing up on the desk with a jeweller's loupe and doing A/B comparisons between the 4k scaled and 5k, you won't notice.

What you will notice is colour differences between the iMac's P3 display and a standard-gamut 4k. You can reduce that with calibration but, at the end of the day, a wide-gamut display can reproduce colours that a standard gamut can't.

The extra GPU load might cause lag on a Mac Mini or lower-end MacBook with with a relatively feeble iGPU, but The 5k iMacs all have half-decent GPUs and dedicated VRAM.

If you've seen the (awful) result of (say) scaling 1440p to 1080p on a 'non-retina' display, try and put that out of your head - MacOS scaling on "retina" class displays is in a different league.

Plus, it only takes a jiffy to switch it to either 1:1 4k resolution or pixel-doubled "looks like 1080p" mode to get unqualified 4k resolution when you need it. The main reason for using scaled mode is to get the size of system fonts, menus and dialogs "just right" - if you're displaying a full-screen image or even a window full of text that doesn't matter much - virtually every application lets you choose the magnification used for 'content'.

That said, going for 1440p secondary display(s) is a perfectly sensible way of saving a few hundred bucks c.f. buying (possibly two) 4k displays, given that you're mostly going to be focussing in the primary 5k, but I don't think you can justify it on "quality" grounds.
Thank you very much, these are all the things going through my head that I'm trying to figure out. I use to use a 2012 imac with two thunderbolt displays scaled to 1600 x 900 to get the font size right. Once I saw the retina display I've been trying to find out how to replicate that with the higher displays.
 

theluggage

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Jul 29, 2011
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I use to use a 2012 imac with two thunderbolt displays scaled to 1600 x 900 to get the font size right. Once I saw the retina display I've been trying to find out how to replicate that with the higher displays.
I take it from that that you don't like the default setting of 2560x1440 on the 27" iMac (or 'looks like 2560x1440" on the 5k)? Because a 2012 iMac and thunderbolt display are both native 2560x1440 (probably exactly the same panel) and should have produced matching displays.

On a 4k display, 1600x900 isn't one of the standard 5 options offered in the 'Displays Preferences' box, but if you
Option-click on the 'Scaled' button to get the full resolution list - you'll get an extended list of options including 1600x900. With a 4K display those are all 'looks like' modes and what you actually get is 3200x1800 at 2x scale, re-sampled to the idsplay's native 3840x2160 which gives the same font size but with considerably more detail and fewer 'artifacts' than 'actual' 1600x900. On an old TB display you'd just have got 1600x900 scaled up to 2560x1440, which would have been pretty grotty by comparison.

Technically, at 4k, "looks like 1920x1080" is the optimum mode as it is exactly half the native resolution, but there's no option to set the 5k display to 'looks like 1920x1080' (maybe with a 3rd party utility like SwitchResX - but Apple probably left it out for a reason). In terms of GPU load, unless you're obsessive about all three displays being exactly the same but want larger fonts, I'd probably keep the 4ks at ll 1920x1080 which isn't too different from either 1600x900 or 2048x1152 on the main screen.

If you do want all 3 exactly the same, your choices are (looks like) 1600x900, 2048x1152 and 2560x1440 (which I'm assuming is too small for you, although its optimum for the 5k).
 
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AlexJoda

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Apr 8, 2015
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Thank you for the info. Is your monitor the P27H-10? Or is it a P27H? First I'm hearing about this monitor, I like the way they look next to an imac but I'm not sure I'm looking at the right one.
It is the P27H. I think it fits very good to the design of the iMac because you don’t notice it very much with it’s small bezels and it has a noticeable sharper look than many other 1440p displays I compared it to. It also has USB-C daisy chaining and some USB-A ports including one with high power to recharge iPhones and so on.

I like an unscaled or a 2:1 scaled (like the 5k display) picture better than a downsampled picture. You may go and compare it for yourself in a shop....
 
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bodhisattva1123

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I take it from that that you don't like the default setting of 2560x1440 on the 27" iMac (or 'looks like 2560x1440" on the 5k)? Because a 2012 iMac and thunderbolt display are both native 2560x1440 (probably exactly the same panel) and should have produced matching displays.

On a 4k display, 1600x900 isn't one of the standard 5 options offered in the 'Displays Preferences' box, but if you
Option-click on the 'Scaled' button to get the full resolution list - you'll get an extended list of options including 1600x900. With a 4K display those are all 'looks like' modes and what you actually get is 3200x1800 at 2x scale, re-sampled to the idsplay's native 3840x2160 which gives the same font size but with considerably more detail and fewer 'artifacts' than 'actual' 1600x900. On an old TB display you'd just have got 1600x900 scaled up to 2560x1440, which would have been pretty grotty by comparison.

Technically, at 4k, "looks like 1920x1080" is the optimum mode as it is exactly half the native resolution, but there's no option to set the 5k display to 'looks like 1920x1080' (maybe with a 3rd party utility like SwitchResX - but Apple probably left it out for a reason). In terms of GPU load, unless you're obsessive about all three displays being exactly the same but want larger fonts, I'd probably keep the 4ks at ll 1920x1080 which isn't too different from either 1600x900 or 2048x1152 on the main screen.

If you do want all 3 exactly the same, your choices are (looks like) 1600x900, 2048x1152 and 2560x1440 (which I'm assuming is too small for you, although its optimum for the 5k).
Great info, thankyou. I never knew about the option click. Yes on my 2012 the 2560x1440 was too small. I use to be fine with the 1600x900 until I saw the retina displays and then it looked like crap. So now I'm trying to match that same setup with the 5k imac. My ocd kind of kicks in also not having an option to buy an "apple" monitor. Even though the thunderbolts were shorter they were essentially the same panel, minus the chin. Or I could buy a mac pro and 3 of the 6,000 dollar apple screens to get everything to match.... :|
- - Post merged: - -

It is the P27H. I think it fits very good to the design of the iMac because you don’t notice it very much with it’s small bezels and it has a noticeable sharper look than many other 1440p displays I compared it to. It also has USB-C daisy chaining and some USB-A ports including one with high power to recharge iPhones and so on.

I like an unscaled or a 2:1 scaled (like the 5k display) picture better than a downsampled picture. You may go and compare it for yourself in a shop....
It is the P27H. I think it fits very good to the design of the iMac because you don’t notice it very much with it’s small bezels and it has a noticeable sharper look than many other 1440p displays I compared it to. It also has USB-C daisy chaining and some USB-A ports including one with high power to recharge iPhones and so on.

I like an unscaled or a 2:1 scaled (like the 5k display) picture better than a downsampled picture. You may go and compare it for yourself in a shop....
I"m going to look into that monitor further. Thanks for the great info alexjoda.