Question Dual GPU Setup issue - monitors not working with PCIe 2.0 card during boot ?

[gpu_man]

Hello everyone,

I'm experiencing a perplexing issue with my dual GPU setup and could use some expertise. My system configuration is as follows:

• Motherboard: ASUS Z87-PRO
• GPUs: NVIDIA RTX 3090 (in PCIe 3.0/2.0 x16 slot) and NVIDIA GTX 960 (in PCIe 2.0 x16 slot, operating at max x4 mode)
• Objective: I want to use the GTX 960 exclusively for my monitor outputs, with no monitors connected to the RTX 3090, which is intended for computational tasks.
• Problem: When only the GTX 960 is connected to monitors, my system fails to boot into Windows. There's no output on the monitors during the boot process, and it seems like the system hangs or doesn't initiate the boot sequence correctly.

Additional information:

• Both GPUs are recognized in Windows Task Manager when the system successfully boots with monitors connected to the RTX 3090 or one monitor connected to the RTX 3090 and one connected to GTX 960.
• If I connect a monitor to the RTX 3090, the system boots up normally, but this setup doesn't align with my intended use.
• I have not found options in the BIOS settings to explicitly designate the GTX 960 as the primary display adapter.

I'm trying to determine if this issue is a result of BIOS/motherboard configuration, a compatibility problem, or something else. Has anyone encountered a similar situation or can provide insights into how to make the GTX 960 the primary output for display, especially for the boot process?

I appreciate any advice or suggestions you can offer!

 

[helpstar]

update the BIOS of the motherboard

use the motherboard´s video ports and the iGPU of your CPU, if present, instead of the 960

seat the GTX960 into the 1st PCIe slot and the 3090 to the 2nd PCIe (reduced bandwidth for your 3090, but your 960 should be able to boot)

maybe launching CSM enabled could work
set the option "boot from PCIe..." to legacy oprom first
with this option, windows might not boot anymore if installed with GPT and UEFI

 

[gpu_man]

Thank you, @helpstar , will try!