Multiple displays no longer working with recommended NVIDIA Driver

Distribution

Mint 22.1

Package version

6.4.8

Graphics hardware in use

NVIDIA GeForce RTX 4070 Ti

Frequency

Always

Bug description

Multiple displays do not work with recommended nvidia driver version 575 but does not occur on 570. The display settings / nvidia-settings appear to see the correct displays and show them as active. However, the Dell 24" display is showing no DP input.

Below is the system information:

Kernel: 6.14.0-28-generic #28~24.04.1-Ubuntu SMP PREEMPT_DYNAMIC Fri Jul 25 10:47:01 UTC 2 x86_64 x86_64 x86_64 GNU/Linux

NVIDIA Driver Version: 575.64.03

NVML Version: 12.575.64.03

Display Server: X11 (v1.21.1.11)

dmesg | grep nvidia:

[   11.040314] nvidia: loading out-of-tree module taints kernel.
[   11.040321] nvidia: module verification failed: signature and/or required key missing - tainting kernel
[   11.093136] nvidia-nvlink: Nvlink Core is being initialized, major device number 234
[   11.095276] nvidia 0000:01:00.0: vgaarb: VGA decodes changed: olddecodes=io+mem,decodes=none:owns=io+mem
[   11.164325] nvidia-modeset: Loading NVIDIA UNIX Open Kernel Mode Setting Driver for x86_64  575.64.03  Release Build  (dvs-builder@U22-I3-H04-03-5)  Wed Jun 25 18:07:44 UTC 2025
[   11.168014] [drm] [nvidia-drm] [GPU ID 0x00000100] Loading driver
[   12.891731] [drm] Initialized nvidia-drm 0.0.0 for 0000:01:00.0 on minor 1
[   12.891757] [drm] [nvidia-drm] [GPU ID 0x00000100] Encoder with NvKmsKapiDisplay 0x00000001 already exists.
[   12.921391] nvidia 0000:01:00.0: vgaarb: deactivate vga console
[   12.996887] fbcon: nvidia-drmdrmfb (fb0) is primary device
[   12.996890] nvidia 0000:01:00.0: [drm] fb0: nvidia-drmdrmfb frame buffer device

inxi -G:

Graphics:
  Device-1: NVIDIA AD104 [GeForce RTX 4070 Ti] driver: nvidia v: 575.64.03
  Display: x11 server: X.Org v: 21.1.11 with: Xwayland v: 23.2.6 driver: X:
    loaded: nvidia unloaded: fbdev,modesetting,nouveau,vesa
    gpu: nvidia,nvidia-nvswitch resolution: 1: 1920x1080~60Hz 2: 2560x1440
  API: EGL v: 1.5 drivers: nouveau,nvidia,swrast
    platforms: gbm,x11,surfaceless,device
  API: OpenGL v: 4.6.0 compat-v: 4.5 vendor: nvidia mesa v: 575.64.03
    renderer: NVIDIA GeForce RTX 4070 Ti/PCIe/SSE2

Steps to reproduce

Use above Nvidia Driver and Kernel version with Mint 22.1 with 2 DP displays.

Expected behavior

Both displays should work.

Additional information

Start by reproducing this on Mint 22.1 with kernel 6.14.0-28-generic, NVIDIA 575.64.03, X11, and two DP displays; compare the result with driver 570. Inspect the supplied dmesg | grep nvidia and inxi -G output while investigating. Done means both displays work with the recommended driver.