No Video Output From Discrete GPU Until Windows Login Screen

[mrblithe]

Hey everyone,

I've connected my monitor to my RTX 4090 using an HDMI 2.1 cable. Despite both the monitor and GPU supporting this connection, I can't get a video signal until the Windows login screen appears. Curiously, using the HDMI port on the iGPU works as expected (shows all booting process)

Also, If try to access the BIOS by spamming the DEL key during boot, I can confirm that the motherboard shows an A9 Q-code (computer has entered into BIOS) but no signal from the monitor if RTX 4090 is connected.

However, apart from these issues, RTX 4090 works perfectly fine in games and other applications. I've already installed the latest Nvidia drivers and performed a fresh installation of Windows.

I tried these:

Fast boot enable/disable: No luck

XMP enable/disable: No - luck

System Agent Configuration > Graphics Settings > Enable/Disable Multi Monitor: No luck

System Agent Configuration > Graphics Settings > Change primary gpu to PEG: No luck also defaults to CPU after restart.

My System:

CPU: Intel i9 14900k

MOBA: Asus ROG Maximus Z790 Hero Intel Z790

GPU: Asus ROG Strix GeForce RTX 4090 OC Edition 24GB GDDR6X

RAM: GSKILL 64GB (2x32GB) Trident Z5 RGB 6400MHz CL32 DDR5 1.4V F5-6400J3239G32GX2-TZ5RK

PSU: MSI PSU MEG AI1300P PCIE5 1300W 80+ PLATINUM

BIOS Version: 1801 2023/12/22 (latest)

Nvidia Driver: 551.23

[mrblithe]

I believe I've identified the issue. My monitor defaults to HDMI 2.1 version, but without GPU drivers initialized, HDMI 2.1 isn't functional. This is likely because my monitor's resolution is 4K. If I downgrade the HDMI version to 1.4 on my monitor, I'm able to observe the entire boot process and access the BIOS while using my discrete GPU.