Bad quality in secondary monitor

Help
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1

Hello,

I’ve recently installed Arch Linux + KDE Plasma. I love the system so far, and I’ve been able to fix and customize everything I’ve wanted, but there’s one thing that I haven’t been able to fix, and I’m honestly lost about where to start. I have two monitors, my main monitor looks great, as it is supposed to look, but my secondary monitor looks weird, like the image is not antialiased, is just look bad.

Can anyone give me a hand or a hint about how can I fix this? I’ve been searching for days but at this point I don’t know what to do next.

System details

OS: Arch Linux x86_64
Kernel: Linux 6.14.7-arch2-1
DE: KDE Plasma 6.3.5
WM: KWin (Wayland)
GPU: AMD Radeon RX 570 Series [Discrete]

This is kscreen-doctor -o

Output: 1 DP-2
        enabled
        connected
        priority 1
        DisplayPort
        Modes:  1:1920x1080@60!  2:1920x1080@165*  3:1920x1080@144  4:1920x1080@120  5:1920x1080@100  6:1920x1080@60  7:1920x1080@60  8:1920x1080@50  9:1680x1050@60  10:1280x1024@75  11:1280x1024@60  12:1440x900@60  13:1280x960@60  14:1280x800@60  15:1152x864@75  16:1280x720@60  17:1280x720@60  18:1280x720@60  19:1280x720@50  20:1440x576@50  21:1440x576@50  22:1024x768@75  23:1024x768@70  24:1024x768@60  25:1440x480@60  26:1440x480@60  27:1440x480@60  28:1440x480@60  29:800x600@75  30:800x600@72  31:800x600@60  32:800x600@56  33:720x576@50  34:720x576@50  35:720x480@60  36:720x480@60  37:720x480@60  38:720x480@60  39:640x480@75  40:640x480@73  41:640x480@67  42:640x480@60  43:640x480@60  44:640x480@60  45:720x400@70  46:1280x1024@60  47:1024x768@60  48:1280x800@60  49:1920x1080@60  50:1600x900@60  51:1368x768@60  52:1280x720@60 
        Geometry: 0,749 1920x1080
        Scale: 1
        Rotation: 1
        Overscan: 0
        Vrr: Automatic
        RgbRange: unknown
        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 70% and dimming to 100%
Output: 2 HDMI-A-1
        enabled
        connected
        priority 2
        HDMI
        Modes:  53:1920x1200@60*!  54:1920x1080@60  55:1920x1080@60  56:1920x1080@60  57:1920x1080@50  58:1920x1080@24  59:1920x1080@24  60:1600x1200@60  61:1680x1050@60  62:1280x1024@75  63:1280x1024@60  64:1440x900@60  65:1280x800@60  66:1152x864@75  67:1280x720@60  68:1280x720@60  69:1280x720@60  70:1280x720@50  71:1024x768@75  72:1024x768@60  73:800x600@75  74:800x600@60  75:720x576@50  76:720x576@50  77:720x480@60  78:720x480@60  79:720x480@60  80:720x480@60  81:720x480@60  82:640x480@75  83:640x480@60  84:640x480@60  85:640x480@60  86:720x400@70  87:1600x1200@60  88:1280x1024@60  89:1024x768@60  90:1280x800@60  91:1920x1080@60  92:1600x900@60  93:1368x768@60  94:1280x720@60 
        Geometry: 1920,0 1200x1920
        Scale: 1
        Rotation: 2
        Overscan: 0
        Vrr: incapable
        RgbRange: unknown
        HDR: incapable
        Wide Color Gamut: incapable
        ICC profile: none
        Color profile source: sRGB
        Color power preference: prefer efficiency and performance
        Brightness control: unsupported
2

Hi! Just checking, does the unexpected appearance of things on the second monitor come through in screenshots, or do screenshots look as expected?

If screenshots show the issue as well, could you share one here so folks might be able to see what it looks like?

3

Also, you might try to match the geometry of the second monitor with the first monitor i.e. 1920x1080@60. Currently, the second monitor is bumped up to 1920x1200@60. It really shouldn’t matter if the two monitors have worked like this before..

4

Hi buddy,

I’ve tried replicating the appearance in screenshot, but no success. Screenshots shows the content on the second monitor as it should be (when I see the screenshot in my main monitor, of course). Let me attach one image that I took, but I think the image doesn’t show a lot what it looks like.

photo issue
photo issue1280×960 98.8 KB

That picture shows the terminal divided between the two screens. The main one looks good (left) but the secondary one (right side) looks like the font is not antialiased, borders doesn’t look sharp even in icons and applications. This is really noticeable in small fonts. In videos I can tell the difference, it doesn’t look sharp.

Here’s the same image but screenshotted

screenshoot issue
screenshoot issue1415×937 162 KB

@eeyore I don’t know how to reply two messages at the same time! About the monitor, the native resolution of my secondary monitor is 1920x1200, so the resolution is actually the correct one. If you’re curious about the resolution difference being the cause, I’ve trying changing the resolution to 1920x1080@60 and the it doesn’t make any difference in the issue.

5

Thanks - just curious, does the second monitor still look fuzzy if it’s the only one connected?

6

Yes. I’ve tried removing my main monitor from my graphic card and having the secondary monitor only, but the issue still happens. I have one of my monitors (secondary) with HDMI and one with DP (primary) if that’s any useful

7

You have some rotation.
Dose disabling rotation change anything (just to test) ?
Same question about VRR (on the primary monitor) ?

The fact the screenshot looks corrects, means the rendering was fine, so just the blit to screen has some issue.

8

Hi, yeah, my secondary monitor is vertical.

I’ve rotated the monitor back to horizontal and nothing changed. I’ve also disabled VRR changing Adaptative Sync option to Never and it didn’t improve. I’ve noticed something in the photo I shared before (not the screenshot, the one with the real look of the monitors). I don’t know if it’s useful, but can you notice that the terminal seems to be smaller in height in the secondary monitor, even with both monitors in 1920 height resolution?

I suppose the image output is not equal 1920x1200

9

IMG_20250530_042508
IMG_20250530_0425081920×1440 329 KB

I think this image describe the issue way better. Notice how clear the text is in the main monitor and how the text in the secondary one seems like it is lacking pixels. Is there any way I can check the DPI the monitor is running?

My monitor is a Dell U2413 - it should run on 1920x1200@60 having 92dpi (according to the monitor technical specifications) and I feel is running way above, if it is even possible

10

How about the other monitor, it seems they don’t have the same dpi. That would explain the offset.

What if you select another resolution for for second monitor ? Like 1920x1080?

Ports might have something to do with it, checking the HDMI plug doesn’t cost much. (I have seen myself similar issue with a not fully plugged-in HDMI cable).
Or using only DP or switch ports between the screens could be interesting.
Also make sure your screens are plugged in the GPU not the motherboard (just worth mentioning).

11

I forgot to say, but I think it’s useful, that I’ve been using this monitor as a secondary for years in my Windows installation with no issues. That’s why I was able to tell the difference immediately when I installed Arch.

According to this pages: 24" Dell UltraSharp U2413 - Specifications | 23.8" Asus TUF Gaming VG247Q1A - Specifications - my secondary monitor actually has better DPI than my main monitor (not for much), so they should look pretty much the same in the comparison.

Changing the resolution to 1920x1080 stretched the image as expected, but it basically looks the same, doesn’t look sharp. I just plugged again both sides of the HDMI connections, and in GPU side I’ve changed it to my other HDMI output. Sadly, my secondary monitor’s DP input port is broken, so I can’t test both in DP (I recently found out this, and made sure that the cable is not faulty).

My CPU doesn’t have integrated graphics, so plugging it to the motherboard wouldn’t do much :joy: