LG UltraFine 5K Build

[joevt]

Great; I'll check tomorrow when I am back home.

When I tried my native 3840x2160 display, the pixel clock rate was showing as 600Mhz ---- does that sound right for 4K?

4K is more like 533 MHz. Maybe if you take a screen shot of where you got that 600 MHz from, then we can figure out why it says 600 MHz.

 

[Attila]

4K is more like 533 MHz. Maybe if you take a screen shot of where you got that 600 MHz from, then we can figure out why it says 600 MHz.

Okay. So I am now connected to my LG 4K display --- native resolution of 3840x2160.

When first installing OSX, the resolution defaults to 1920x1080. As you can see from my pic 'scr1', I select "More Space -- Looks like 3840x2160" from the Scaled option in System Prefs.

In my picture 'scr2', you can see the correct info in the System Profiler --- 3840x2160 @60Hz.

The last pic 'scr3', shows a screen from SwitchResX with the frequencies I was talking about.

 

[joevt]

The last pic 'scr3', shows a screen from SwitchResX with the frequencies I was talking about.

Those are the ranges allowed by the display. A resolution uses a single frequency (not a range) for horizontal, vertical, and pixel clock. Go to the Current Resolutions tab, double click a resolution to see the timing info for that resolution. Post a screen shot (command-shift-4, press space bar, and click a window, or command-shift-4 and select an area, press escape to cancel if necessary, command-shift-3 for the whole screen) for the 4K and 5K resolutions (when you connect the 5K).

 

[Attila]

Those are the ranges allowed by the display. A resolution uses a single frequency (not a range) for horizontal, vertical, and pixel clock. Go to the Current Resolutions tab, double click a resolution to see the timing info for that resolution. Post a screen shot (command-shift-4, press space bar, and click a window, or command-shift-4 and select an area, press escape to cancel if necessary, command-shift-3 for the whole screen) for the 4K and 5K resolutions (when you connect the 5K).

Thanks -- I'll do that when I get home from work today. In the meantime, I do have another question:

In Windows 10, the "Display Settings" allows you to change/magnify/scale the size of icons.text,etc. on the screen (100%,150%, etc., while maintaining a specific display resolution (e.g. 3840x2160). Naturally, this makes things more readable at higher resolutions on smaller displays.

Using OSX, how can you do this? Let's say I go into the Display/scaled options and select "More Space --- Looks like 3840x2160". If I want things to look larger, I could select say, "Looks like 2560x1440". However the problem is, if I do that the System Profile/"Graphics-Displays" section (where it shows the video card and monitor info) will tell me that the display resolution is 2560x1440. But that is not what I want --- I want to keep the 3840x2160, but just make text,icons, etc. more readable (larger).

Hopefully my question is clear....

 

[joevt]

In Windows 10, the "Display Settings" allows you to change/magnify/scale the size of icons.text,etc. on the screen (100%,150%, etc., while maintaining a specific display resolution (e.g. 3840x2160). Naturally, this makes things more readable at higher resolutions on smaller displays.

Using OSX, how can you do this? Let's say I go into the Display/scaled options and select "More Space --- Looks like 3840x2160". If I want things to look larger, I could select say, "Looks like 2560x1440". However the problem is, if I do that the System Profile/"Graphics-Displays" section (where it shows the video card and monitor info) will tell me that the display resolution is 2560x1440. But that is not what I want --- I want to keep the 3840x2160, but just make text,icons, etc. more readable (larger).

Hopefully my question is clear....

For any given resolution, macOS supports 100% and 200% scaling. The 200% scaling resolutions are called HiDPI.

The "Looks Like 2560 x 1440" is actually drawn in a 5120 x 2880 frame buffer by the OS using 200% scaling (lines are double thick, fonts are quadruple the size (double the width and double the height), menu and title bars are twice as tall, etc). The frame buffer is then scaled for output by the graphics card. The display may perform an additional scaling step (for example, a 4K display may allow a 1080p input, which it will scale to 4K).

I believe Mac OS X in the past allowed different scaling factors via a Quartz debug app, but Apple has settled on supporting only 200%. It simplifies the testing that developers have to do (also reduces the number of icon sizes they have to create).

If you want 3840x2160 then your only option is "Looks like 1920 x 1080". Any other option will draw into a smaller or larger frame buffer.

 

[bart613]

Just wanted to follow-up this thread saying - thank you; it intrigued me to have a look at my old (well, from around Sep / 2017) Hackintosh in relation to getting something that can drive the LG 5k screen I bought, in capacity that was actually usable (Macbook Pro 13" mid-2017 w/ Touchbar is a no go for anything above web-browsing).

Initially I built my Hackintosh with EVGA GeForce 1060 GTX SC 6GB and Asus STRIX Z270G GAMING motherboard, but since the LG 5k needed TB3 cable via ASROCK THUNDERBOLT 3 AIC adapter, I tried the Asrock Z270M EXTREME4 with the adapter ... and also converted to the slower Radeon RX 580 to avoid the GeForce GTX 1050/1060 sleep wake-up issue and get more native support.

I've been working 100% time on the Hackintosh connected to LG 5k screen working at 5k resolution for a week now; it's stable and everything is working as expected. And speed of the thing is just mind-blowing.

One thing I had to do to avoid the issue with having 4K resolution working on LG 5k screen (or OS showing 2 screens - 1 4K and 1 1024x768??! Or having to force 5K resolution via 3rd party software; or 5K resolution but 30/40Hz) was to switch the system profile to Mac Pro (Late 2013); after I've done that, OS comes up with 5K screen only and everything works on the LG 5k screen - camera, setting brightness, audio.

Thanks again for making me look into this stuff again; the LG 5k screen is just mind-blowing and years ahead of anything available on the market (please don't get me even started about the overpriced Dell UP2718...).

 

[Attila]

For any given resolution, macOS supports 100% and 200% scaling. The 200% scaling resolutions are called HiDPI.

The "Looks Like 2560 x 1440" is actually drawn in a 5120 x 2880 frame buffer by the OS using 200% scaling (lines are double thick, fonts are quadruple the size (double the width and double the height), menu and title bars are twice as tall, etc). The frame buffer is then scaled for output by the graphics card. The display may perform an additional scaling step (for example, a 4K display may allow a 1080p input, which it will scale to 4K).

I believe Mac OS X in the past allowed different scaling factors via a Quartz debug app, but Apple has settled on supporting only 200%. It simplifies the testing that developers have to do (also reduces the number of icon sizes they have to create).

If you want 3840x2160 then your only option is "Looks like 1920 x 1080". Any other option will draw into a smaller or larger frame buffer.

Still on the 4K, I went to Display/scaled and set 1920x1080. I have attached two screenshots. First is from double-clicking "Current Resolution" in SwitchResX, and second is from System Report. You'll note that the System Report shows 1920x1080 --- is that normal?

 

[joevt]

Still on the 4K, I went to Display/scaled and set 1920x1080. I have attached two screenshots. First is from double-clicking "Current Resolution" in SwitchResX, and second is from System Report. You'll note that the System Report shows 1920x1080 --- is that normal?

Right, that 1920x1080 is a HiDPI mode, it double width/height graphics (200% scaled) to a frame buffer that is 3840x2160. The frame buffer is output as 3840x2160 (no scaling) to your 4K display.
I suppose System Report shows the HiDPI resolution instead of the actual resolution. This makes it useless for our purposes, since there's no way to determine from that whether it's the 1920x1080 HiDPI mode or the 1920x1080 low resolution mode.

The Displays preferences panel has a check box "Show low resolution modes" where you can try "1920 x 1080 (low resolution)" and compare it with "1920 x 1080" (the HiDPI mode). Just hold the option key and click "Scaled" to see that check box.

Try taking a screen shot of a small window in both resolutions (command-shift-4 and space bar and click a window), then compare them in Preview.app in both resolutions. You should be able to see how the scaling works.

 

[bart613]

Still on the 4K, I went to Display/scaled and set 1920x1080. I have attached two screenshots. First is from double-clicking "Current Resolution" in SwitchResX, and second is from System Report. You'll note that the System Report shows 1920x1080 --- is that normal?

This is weird, even when I had 4K resolution on my LG 5K screen, it still was showing up as LG UltraFine screen in System Report.

After switching to System Profile being Mac Pro I didn't even have to install SwitchResX - it worked as a single 5K screen out-of-the-box.

Slightly worried as I have Vega 64 on order - hope it'll work as flawlessly with it as with current Radeon.

 

[Attila]

Right, that 1920x1080 is a HiDPI mode, it double width/height graphics (200% scaled) to a frame buffer that is 3840x2160. The frame buffer is output as 3840x2160 (no scaling) to your 4K display.
I suppose System Report shows the HiDPI resolution instead of the actual resolution. This makes it useless for our purposes, since there's no way to determine from that whether it's the 1920x1080 HiDPI mode or the 1920x1080 low resolution mode.

The Displays preferences panel has a check box "Show low resolution modes" where you can try "1920 x 1080 (low resolution)" and compare it with "1920 x 1080" (the HiDPI mode). Just hold the option key and click "Scaled" to see that check box.

Try taking a screen shot of a small window in both resolutions (command-shift-4 and space bar and click a window), then compare them in Preview.app in both resolutions. You should be able to see how the scaling works.

I'll run some tests tonight with the 5K LG 5K and report back.