Dear Qubes Community,
I hope this message finds you well. I am a new Qubes OS user, and I have been trying to install Qubes OS 4.3.1 on my hardware over the past few days. I have read the official documentation and many community threads, but I am currently stuck and would really appreciate your guidance.
My Hardware:
Motherboard: ASUS Z790 (BIOS fully updated)
CPU: Intel Core i9-13900K (with Intel UHD 770 integrated graphics)
GPU: NVIDIA GeForce RTX 4090
RAM: 64GB DDR5
Storage: 1TB NVMe SSD
My Goal:
I would like to use the UHD 770 iGPU for dom0 display output, and later pass through the RTX 4090 to an AppVM (HVM) for GPU-intensive workloads (e.g., AI inference or gaming). I understand this is a complex setup, and I am willing to learn.
The Problem – Installation Phase:
When I boot from the Qubes OS 4.3.1 USB installer, the system starts GRUB, but immediately after selecting the boot option, my monitor loses signal and shows “No Signal”. I never see the Anaconda installer screen.
I tried the official documentation’s advice for NVIDIA cards, which suggests adding parameters to the kernel line. However, I could not find a line starting with kernel= in the GRUB editor—only a line starting with linux (I believe the documentation may be outdated). I added the suggested parameters after the quiet keyword instead, as shown below:
text
nouveau.modeset=0 rd.driver.blacklist=nouveau video=vesa:off
I also tried the alternative set of parameters:
text
noexitboot=1 modprobe.blacklist=nouveau rd.driver.blacklist=nouveau — initrd.img
Unfortunately, neither of these worked. The monitor still went into “No Signal” mode.
Eventually, I found that adding inst.vnc to the parameters allowed me to proceed with the installation via VNC (using port 5901). This was a workaround, but it did not solve the underlying graphics issue.
The Problem – Post-Installation:
After successfully installing Qubes via VNC and rebooting, I faced the same issue: the system boots, but LightDM never starts, and the graphical login screen does not appear. I can still switch to tty2 (Ctrl+Alt+F2) and log into dom0 via the command line.
When I try startx, I get the classic error:
text
(EE) no screens found
(EE) Server terminated with error (1)
What I Have Tried So Far (Without Success):
BIOS Settings (ASUS Z790):
I changed Primary Display from Auto/PCIE to CPU Graphics (to force iGPU priority).
I enabled iGPU Multi-Monitor.
I set DVMT Pre-Allocated to 256M.
I enabled VT-d and VT-x.
I enabled Above 4G Decoding and disabled Resizable BAR (I also tried the opposite).
I enabled Control Iommu Pre-boot Behavior (and also tried disabling it).
GRUB Kernel Parameters (tried various combinations in /etc/default/grub):
modprobe.blacklist=nouveau rd.driver.blacklist=nouveau
i915.force_probe=*
rd.qubes.hide_pci=01:00.0,01:00.1 (this caused the system to shut down immediately after GRUB)
I also tried nomodeset and i915.modeset=1
After each change, I ran sudo grub2-mkconfig -o /boot/grub2/grub.cfg and rebooted.
Physical Display Connections:
I confirmed that my monitor cable is plugged into the motherboard’s HDMI/DP port (not the RTX 4090).
Verification:
lspci | grep -i vga shows both the UHD 770 (00:02.0) and the RTX 4090 (01:00.0).
lspci -k | grep -A 2 VGA shows that the i915 driver is not binding to the iGPU, and the nouveau driver is still trying to claim the RTX 4090 despite being blacklisted.
Despite all these attempts, the system still hangs at Starting lightdm.service - Light Display Manager during boot. Xorg refuses to start, and the log file shows (EE) no screens found.
My Questions to the Community:
BIOS settings: Could someone with an ASUS Z790 (or similar) board share a definitive list of BIOS settings required for Qubes OS to correctly recognize and use the UHD 770 iGPU for dom0, while allowing the RTX 4090 to be reserved for later passthrough? Are there any specific options I might have missed (e.g., IGD Multi-Monitor, RC6, or anything under PCI Subsystem Settings)?
GRUB parameters: Where exactly should I add the parameters in the modern GRUB configuration (since the documentation mentions a kernel= line that no longer exists)? What is the correct and complete set of parameters to force Qubes to:
Blacklist nouveau completely,
Force-load the i915 driver for the UHD 770,
Ignore/hide the RTX 4090 from dom0 (without causing an immediate shutdown)?
I noticed that rd.qubes.hide_pci=01:00.0,01:00.1 caused a sudden power-off, which seems unusual—has anyone experienced this, and is there a different way to hide the GPU?
Kernel version: Would updating to kernel-latest help with iGPU compatibility? If so, could you guide me on how to install it from the text console (tty2) since I do not have a graphical environment?
Xen/hypervisor interaction: Could Xen be interfering with the iGPU initialization? Is there any Xen-specific parameter I should add to allow dom0 to properly use the i915 driver?
Alternative approach: Should I temporarily install a lightweight desktop environment or use a different display manager to debug the Xorg issue, or is this purely a driver/kernel parameter problem?
Additional Information:
I have read the official Qubes documentation on NVIDIA GPUs and the GPU passthrough guide.
I have also searched the community forums and Reddit but could not find a definitive solution for the combination of ASUS Z790 + 13900K + RTX 4090.
I am happy to provide any logs you need (e.g., Xorg.0.log, dmesg, journalctl -xe) upon request. I genuinely want to make Qubes work on this hardware, and I appreciate any time and expertise you can offer.
Thank you very much for reading, and I look forward to your suggestions.
Best regards,
Hi quber2025 - and welcome! 
Did you go with the default kernel or the kernel-latest? – you can check with
uname -a
I’m not sure about the correct driver for the UHD 770 card .. but there are some notes about missing drivers for Xe-graphics - eg:
– I don’t know if it’s relevant for you (I have old hardware), so it’s only a suggestion …
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thanks so much sir But I feel like it didn’t solve my problem, but I sincerely respect
Your issue seems to be that Xorg still try to use your nvidia card while having no suitable driver for it. Check dmesg in dom0, you will probably see drivers errors saying that 4090 is not supported; it can be usefull to debug. You probably need to configure satan xorg.conf to force it to not try to use nvidia card. Try that GPU Passthrough -> lightdm.service won't start - #20 by light it could help. Create a Gaming HVM .
I had the same issue that I solved on similar hardware a year ago, but I don’t have access to it currently and don’t remember what I exactly did
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