Steam detects wrong primary monitor

[evanc577]

Your system information

• Steam client version: 1721173382 (Flatpak version)
• Distribution: Arch Linux
• Opted into Steam client beta?: Both
• Have you checked for system updates?: Yes
• Steam Logs: N/A
• GPU: AMD 7900 XTX
• DE: KDE Plasma 6.1.3 (Wayland)

Please describe your issue in as much detail as possible:

In a triple monitor setup, Steam detects the leftmost monitor as the primary display and opens all content (start splash, fullscreen games, big picture mode, etc.) on that monitor, instead of the actual primary display set in KDE Plasma settings. I only started experiencing this issue recently, after returning from a 3 week vacation, but it was working correctly in June.

Plasma monitor configuration, center screen is set as highest priority:

(expand) Steam system information, note that the display detected is the leftmost 1080p 24 inch vertical display, rather than the other two 4k 144hz horizontal displays.

Computer Information:
Manufacturer: Micro-Star International Co., Ltd.
Model: B450I GAMING PLUS AC (MS-7A40)
Form Factor: Desktop
No Touch Input Detected
Processor Information:
CPU Vendor: AuthenticAMD
CPU Brand: AMD Ryzen 7 5800X3D 8-Core Processor
CPU Family: 0x19
CPU Model: 0x21
CPU Stepping: 0x2
CPU Type: 0x0
Speed: 4548 MHz
16 logical processors
8 physical processors
Hyper-threading: Supported
FCMOV: Supported
SSE2: Supported
SSE3: Supported
SSSE3: Supported
SSE4a: Supported
SSE41: Supported
SSE42: Supported
AES: Supported
AVX: Supported
AVX2: Supported
AVX512F: Unsupported
AVX512PF: Unsupported
AVX512ER: Unsupported
AVX512CD: Unsupported
AVX512VNNI: Unsupported
SHA: Supported
CMPXCHG16B: Supported
LAHF/SAHF: Supported
PrefetchW: Unsupported
Operating System Version:
Freedesktop SDK 23.08 (Flatpak runtime) (64 bit)
Kernel Name: Linux
Kernel Version: 6.10.0-zen1-2-zen
X Server Vendor: The X.Org Foundation
X Server Release: 12401001
X Window Manager: KWin
Steam Runtime Version: steam-runtime_0.20240610.91380
Video Card:
Driver: AMD AMD Radeon RX 7900 XTX (radeonsi, navi31, LLVM 17.0.6, DRM 3.57, 6.10.0-zen1-2-zen)
Driver Version: 4.6 (Compatibility Profile) Mesa 24.1.3 (git-0c49f54c76)
OpenGL Version: 4.6
Desktop Color Depth: 24 bits per pixel
Monitor Refresh Rate: 59 Hz
VendorID: 0x1002
DeviceID: 0x744c
Revision Not Detected
Number of Monitors: 3
Number of Logical Video Cards: 1
Primary Display Resolution: 2880 x 1620
Desktop Resolution: 9300 x 2880
Primary Display Size: 20.75" x 11.65" (23.78" diag), 52.7cm x 29.6cm (60.4cm diag)
Primary VRAM: 24576 MB
Sound card:
Audio device: ATI R6xx HDMI
Memory:
RAM: 32019 Mb
VR Hardware:
VR Headset: None detected
Miscellaneous:
UI Language: English
LANG: en_US.UTF-8
Total Hard Disk Space Available: 1875877 MB
Largest Free Hard Disk Block: 541912 MB
Storage:
Number of SSDs: 6
SSD sizes: 2048G,500G,15G,0B,0B,0B
Number of HDDs: 0
Number of removable drives: 0

Steps for reproducing this issue:

• Open Steam (splash screen is on leftmost monitor)
• Open big picture mode (opens on leftmost monitor)
• Open fullscreen game (opens on leftmost monitor)
• Receive a steam notification (displays on leftmost monitor)

[xyproto]

Should vertical monitors be ignored by Steam if there are more than 1 monitors, would this be a possible solution?

[D33M0N]

Should vertical monitors be ignored by Steam if there are more than 1 monitors, would this be a possible solution?

I would say, no. It should honor the "primary" monitor setting of your desktop compositor. OR let you choose in steam own settings primary monitor to launch games in.

(then again, for me it has always worked in Plasma + Wayland. Had previously issues in XFCE + X11)

[evanc577]

I worked around this issue by running xrandr --output DP-1 --primary to set my primary monitor for X apps.

Maybe this is a KDE bug and it should be setting the X primary monitor even when KDE is running in wayland mode? Not sure whose responsibility this is.

[xyproto]

I wish X/Wayland/KDE/other WMs had a concept of not only "primary monitor" but also "entertainment monitor", for video and gaming.

[rehdi93]

This also happens on Fedora 41 KDE, running Plasma 6.2.2

fix by @evanc577 works but I have to run it every time before starting steam