HD4400 Laptop with 4k monitor

[kevin335200]

3. it seems to solve my previous issue, but max resolution doesn't change
5. i can confirm that in 10.12 it supports 4k, because i have used 1080p HiDPI in order to let screenshot sharper, and you have said that it changes nothing because my screen is still 1080p

Yes i put the file into wrong place.Now it works.Thanks! Perhaps update the new location to your Guide is a good idea
I know that, but i want to get better quality of my screenshot(use HiDPI it will be 4k) so i add this one.

also i use U3417W(3440*1440) as external monitor with 10.12 at that time, but now even this resolution doesn't appear

 

[RehabMan]

3. it seems to solve my previous issue, but max resolution doesn't change
5. i can confirm that in 10.12 it supports 4k, because i have used 1080p HiDPI in order to let screenshot sharper, and you have said that it changes nothing because my screen is still 1080p

also i use U3417W(3440*1440) as external monitor with 10.12 at that time, but now even this resolution doesn't appear

Are you saying you have the same monitor working at 4k on 10.12.x?

 

[kevin335200]

Are you saying you have the same monitor working at 4k on 10.12.x?

not the same, that's the question, i have already sold the precious one.
but previous one works with higher resolution(3440*1440p,not 4k,a little bigger than 2k)
before the real problem is clear i will try to rebuild 10.12.x on my external hard drive in order to see if 10.12.x works

 

[kevin335200]

display override works, but it seems like this under the monitor's resolution 3840*1600:
Black border disappears when using 3840*2160, but of course it isn't the monitor's resolution so the screen stretchs.
from monitor's information i can see that any resolution greater than 2560*1440 outputs actually 1920*1080 signal and stretch it
but it should output at least 3440*1440, which is not 4k and previously works. don't know why

 

[RehabMan]

display override works, but it seems like this under the monitor's resolution 3840*1600:
Black border disappears when using 3840*2160, but of course it isn't the monitor's resolution so the screen stretchs.
from monitor's information i can see that any resolution greater than 2560*1440 outputs actually 1920*1080 signal and stretch it
but it should output at least 3440*1440, which is not 4k and previously works. don't know why

See guide for how to create custom HiDPI modes:
https://www.tonymacx86.com/threads/adding-using-hidpi-custom-resolutions.133254/

 

[kevin335200]

Success with 3440*1440. Still no 3840*1600.
custom HiDPI doesn't work, it's scaled. I use SwitchResX to add a custom resolution and finally get real 3440*1440 output.
For why i can get 3440*1440 directly with U3417W i think it's because of monitor's Preset Display Modes.
U3818DW doesn't have 3440*1440 as preset(see image), so i need to add it manually. Because U3417W's max resolution is 3440*1440, it must be included as preset.
For why macOS doesn't recognize 3840*1600, i think it's HD4400 hardware limit.

I don't sure whether my opinion is right or wrong

 

[RehabMan]

Success with 3440*1440. Still no 3840*1600.
custom HiDPI doesn't work, it's scaled. I use SwitchResX to add a custom resolution and finally get real 3440*1440 output.
For why i can get 3440*1440 directly with U3417W i think it's because of monitor's Preset Display Modes.
U3818DW doesn't have 3440*1440 as preset(see image), so i need to add it manually. Because U3417W's max resolution is 3440*1440, it must be included as preset.
For why macOS doesn't recognize 3840*1600, i think it's HD4400 hardware limit.

I don't sure whether my opinion is right or wrong

Why would you expect to get 3840x1600 when the max resolution of the monitor is 3440x1440?

 

[kevin335200]

Why would you expect to get 3840x1600 when the max resolution of the monitor is 3440x1440?

U3818DW's max resolution is 3840*1600. I'm using now U3818DW.

 

[RehabMan]

U3818DW's max resolution is 3840*1600. I'm using now U3818DW.

You might test your hardware with Windows to discover limitations.

 

[kevin335200]

windows and ubuntu can both run at 3840*1600 60Hz, see #1.
Just don't know why macOS can't.
Now i have tried the max resolution is about 3840*1290 under macOS
But pixel clock patch doesn't work with it