Dual Monitor Setup: Second Monitor Not Detected

Support Graphics & Display
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1

System Information

  • Branch: Stable
  • DE / WM: xfce
  • CPU: Intel i9
  • GPU: GEFORCE RTX 4070 Ti SUPER
  • GPU Driver: video-nvidia 2024.05.03
  • Kernel: 6.9.12-3-MANJARO
  • Bootloader: GRUB
  • Architecture: x86_64

Monitor Information

  • Primary Monitor (connected to GPU): Samsung UN32J4000AF (32-inch HD TV)
  • Secondary Monitor (connected to motherboard): ASUS PB278Q (27-inch WQHD IPS)

Issue Description

I’m trying to set up a dual monitor configuration using two displays with HDMI inputs. My GPU (GEFORCE RTX 4070 Ti SUPER) has one HDMI port, which is currently connected to the Samsung UN32J4000AF (a 32-inch HD TV) and working fine. I’ve connected the ASUS PB278Q monitor to the motherboard’s HDMI port, hoping to use it as a secondary display.

Both displays show output during POST, but only the Samsung TV (connected to the GPU) functions after that. The ASUS monitor (connected to the motherboard) is not detected by the OS.

What I’ve Tried

  1. Checked BIOS settings, but couldn’t find any obvious options for enabling the second monitor or integrated graphics.
  2. Verified that both displays work when connected to the GPU’s HDMI port individually.

Additional Information

  1. Output of lspci | grep -E "VGA|3D":

    *-display                 
    description: VGA compatible controller
    product: AD103 [GeForce RTX 4070 Ti SUPER]
    vendor: NVIDIA Corporation
    physical id: 0
    bus info: pci@0000:01:00.0
    logical name: /dev/fb0
    logical name: /dev/fb1
    version: a1
    width: 64 bits
    clock: 33MHz
    capabilities: pm msi pciexpress vga_controller bus_master cap_list rom fb
    configuration: depth=32 driver=nvidia latency=0 mode=2560x1440 resolution=1366,768 visual=truecolor xres=2560 yres=1440
    resources: iomemory:600-5ff iomemory:640-63f irq:178 memory:81000000-81ffffff memory:6000000000-63ffffffff memory:6400000000-6401ffffff ioport:4000(size=128) memory:82000000-8207ffff
*-display
    description: Display controller
    product: Raptor Lake-S GT1 [UHD Graphics 770]
    vendor: Intel Corporation
    physical id: 2
    bus info: pci@0000:00:02.0
    logical name: /dev/fb1
    version: 04
    width: 64 bits
    clock: 33MHz
    capabilities: pciexpress msi pm bus_master cap_list fb
    configuration: depth=32 driver=i915 latency=0 resolution=2560,1440
    resources: iomemory:640-63f iomemory:400-3ff irq:153 memory:6402000000-6402ffffff memory:4000000000-400fffffff ioport:5000(size=64) memory:4010000000-4016ffffff memory:4020000000-40ffffffff

  2. Output of xrandr:

    Screen 0: minimum 8 x 8, current 1366 x 768, maximum 32767 x 32767
HDMI-0 connected primary 1366x768+0+0 (normal left inverted right x axis y axis) 609mm x 347mm
   1366x768      59.79*+
   1920x1080     59.94    50.00    29.97    25.00    23.98  
   1280x720      60.00    59.94    50.00  
   1024x768      75.03    70.07    60.00  
   800x600       75.00    72.19    60.32  
   720x576       50.00  
   720x480       59.94  
   640x480       75.00    72.81    59.94  
DP-0 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
DP-3 disconnected (normal left inverted right x axis y axis)
DP-4 disconnected (normal left inverted right x axis y axis)
DP-5 disconnected (normal left inverted right x axis y axis)

  3. Output of lsmod | grep -E "nvidia|intel" (condensed for sake of relevance):

    nvidia_uvm           6701056  2
nvidia_drm            126976  10
nvidia_modeset       1605632  10 nvidia_drm
nvidia              60583936  213 nvidia_uvm,nvidia_modeset
intel_rapl_msr         20480  0
intel_rapl_common      40960  1 intel_rapl_msr
intel_uncore_frequency    12288  0
intel_uncore_frequency_common    16384  1 intel_uncore_frequency
intel_tcc_cooling      12288  0
intel_powerclamp       20480  0
kvm_intel             430080  0
intel_cstate           20480  0
intel_uncore          266240  0
intel_pmc_core        122880  0

Questions

  1. Why isn’t my ASUS monitor (connected to the motherboard) being detected, even though both the NVIDIA GPU and Intel integrated graphics are recognized by the system?
  2. Are there specific BIOS settings I should look for to enable using both the dedicated GPU and integrated graphics simultaneously?
  3. Do I need to create a custom Xorg configuration to use both the NVIDIA GPU and Intel integrated graphics?
  4. Is it possible that using a TV (Samsung UN32J4000AF) as my primary display is affecting the dual monitor setup?
  5. The xrandr output only shows HDMI and DP connections. Is there a way to enable or detect the HDMI port on the motherboard?
  6. Are there any additional troubleshooting steps you’d recommend given this information?

I appreciate any guidance on this. Thanks to everyone for your time and attention.

2

If your system is a desktop system, it is usually constructed in a manner that disables the iGPU when you attach a PCIe GPU.

You will likely need to attach both to your Nvidia GPU if you want the setup to work.

I may be wrong - that happens to all of us - but my experience tells me that using a desktop system it is either or - not both.

4

I would certainly be willing to plug both monitors into the video card, but it appears that it only has one HDMI port. It has other ports, but I’m not familiar with them and they don’t appear to be HDMI ports. So maybe I will need some kind of adapter to explore the possibility you are describing. But I don’t yet know for sure.

If there is any way to use both of the two HDMI ports I do have (one on the motherboard, one on the video card), I’d like to explore that option, if possible.

5

The other ports are likely DisplayPort and your nvidia GPU outputs to all ports.

The last decade I have been using Lenovo hardware and when the board provides an iGPU (P330 2gen) and a dGPU is attached it is selectable in firmware which one to use - but it is either iGPU or dGPU - not both.

Using virtualization it is technically possible to utilize both but that is an advanced setup in which I never succeeded accomplishing.

The easiest solution for your situation is to get a DisplayPort cable or an adapter DP to HDMI - do yourself a favor - don’t cheap out on either - you will regret it.

6

Thanks. I’ve now confirmed that the other ports on the video card are indeed display ports. What’s even better is that I’ve also confirmed that the secondary monitor has a single display port on it as well, meaning that an adapter won’t be necessary, and I can solve the whole problem with just a single display port cable. My only question, then, is how to ensure that I get one that meets your minimum quality standard. I don’t know how much they should cost when they are high enough quality to meet such a standard, so I don’t know what price point to investigate. I’d appreciate anything you would like to add on this last point.

7

Be sure the cable matches your monitors highest refresh rate. e.g. 144Hz.

I don’t know what price to expect. I bought 144Hz 8K DP cables a couple of years back. Today, in Denmark, they priced around DKK400 - that is approx. €50 (Supra High End DisplayPort kabel 8K - 144Hz - 2 m)

You can get a decent 4K/60Hz cable for €10.