External monitor goes no signal on Fedora 42 when its correct resolution is chosen

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1

I recently bought a monitor AOC Q27G4XF which is a QHD (2k) monitor capable of 180hz max. I tried connecting it to a windows laptop using HDMI and i was able to achieve 120hz and 2k resolution. Eventually on my fedora 42 laptop using the same hdmi cable it works only on 4k option in the display settings. I have no idea how it upscales to 4k although is 2k monitor. Whenever i choose 2k in settings it just goes no signal and doesnt work. Tried to fix it in terminal with the help of chatgpt but I get a lot of errors and chat gpt told me to buy a DP cable or lightning to DP since my laptop supports it ( Lenovo Thinkpad E14 gen 6) .
Does anyone know the fix ? Im using wayland as i know . Its a fedora 42 with KDE plasma

2

What does kscreen-doctor -o report?
Which gpu so you have?

3 
zlatanoski@fedora:~$ kscreen-doctor -o
Output: 1 eDP-1 d3eba033-c2ec-4a93-ad81-6b586377d6cb
        disabled
        connected
        priority 0
        Panel
        replication source:0
        Modes:  1:1920x1200@60*!  2:1600x1200@60  3:1600x1200@60  4:1280x1024@60  5:1280x1024@60  6:1024x768@60  7:1024x768@60  8:1280x800@60  9:1280x800@60  10:1920x1080@60  11:1920x1080@60  12:1600x900@60  13:1600x900@60  14:1368x768@60  15:1368x768@60  16:1280x720@60  17:1280x720@60 
        Geometry: 778,1543 1829x1143
        Scale: 1.05
        Rotation: 1
        Overscan: 0
        Vrr: Never
        RgbRange: Automatic
        HDR: incapable
        Wide Color Gamut: incapable
        ICC profile: none
        Color profile source: sRGB
        Color power preference: prefer efficiency and performance
        Brightness control: supported, set to 100% and dimming to 100%
        Color resolution: automatic (10), range: [6; 12] bits per color
        Allow EDR: always
Output: 2 HDMI-A-1 e5959e41-da16-4fc5-ac32-19235e8e89c4
        enabled
        connected
        priority 1
        HDMI
        replication source:0
        Modes:  18:2560x1440@60!  19:3840x2160@60*  20:3840x2160@60  21:3840x2160@50  22:2560x1440@144  23:2560x1440@120  24:1920x1080@120  25:1920x1080@120  26:1920x1080@60  27:1920x1080@60  28:1920x1080@60  29:1920x1080@50  30:1280x1440@60  31:1280x1024@75  32:1280x1024@60  33:1280x720@60  34:1280x720@60  35:1280x720@50  36:1024x768@120  37:1024x768@100  38:1024x768@75  39:1024x768@70  40:1024x768@60  41:832x624@75  42:800x600@120  43:800x600@100  44:800x600@75  45:800x600@72  46:800x600@60  47:800x600@56  48:720x576@50  49:720x576@50  50:720x480@60  51:720x480@60  52:720x480@60  53:720x480@60  54:640x480@120  55:640x480@100  56:640x480@75  57:640x480@73  58:640x480@67  59:640x480@60  60:640x480@60  61:640x480@60  62:720x400@70 
        Geometry: 0,0 2954x1662
        Scale: 1.3
        Rotation: 1
        Overscan: 0
        Vrr: incapable
        RgbRange: Automatic
        HDR: disabled
        Wide Color Gamut: disabled
        ICC profile: none
        Color profile source: sRGB
        Color power preference: prefer efficiency and performance
        Brightness control: supported, set to 0% and dimming to 100%
        DDC/CI: allowed
        Color resolution: automatic (10), range: [8; 12] bits per color
        Allow EDR: unsupported

I have integrated intel graphics since its a laptop

4

As you can see the monitor’s EDID does not report any 180Hz modes.
The best is a 120Hz mode which agrees with the monitor spec.

From the monitor spec on | AOC Monitors

DIGITAL SIGNAL FREQUENCY VERTICAL
HDMI2.0: 48-144hz / DP1.4: 48-180hz

It does report a 2560x1440@120 which would avoid any scaling in the monitors .

To use 180Hz you will need to use a DP cable, not HDMI.

5

i tried even 120hz and 144hz was available in the option none work. just goes no signal whenever i choose

6

What exactly did you choose?
The output of the kscreen-doctors should match what you can choose in the GUI.

7

2k 120hz straight from display configuration in the system settings

8

Pick 2560x1440 at 120 does that work.

9

no,
i get no signal

10

Try 2560x1440 at 60 does that work?

11

I wonder if your HDMI cable is not a high enough spec cable?

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12

im thinking of buying lightning to DP but how does the same HDMI cable work on another windows laptop

13

also it works on my fedora 42 but on the resolution 3840x2160 60hz which is confusing why it upscales it, i tried every hz option for the 2k res and it just goes no signal and reverts it after some seconds

14

It is perfectly normal for a cable that is out of specification to sometimes work with one device and then stop working or not function with another. For example, I have an old HDMI 1.4 cable that allows me to use 2160p at 60Hz with one laptop, but it doesn’t work with another.

I definitely recommend trying a different cable, as these cable issues can be quite frustrating.

Actually my recommendation for 4K / 60Hz is to get an HDMI 2.1 cable. They are a bit more expensive, but in my experience, they work much more reliably.

15

it says that in the box is * 1× HDMI cable (HDMI 2.0, supporting up to 1440p @ 144 Hz)
i can try getting hdmi 2.1 which is not expensive here i dont know why it costs like 5 euros

16

chatgpt says that lenovo limits the hdmi 2.1 port to 4k 60hz and says to better get an lightning to DP cable which is quite expensive

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