Can only enter BIOS if monitor is using onboard GPU

[RMPLP]

New build as follows:

ASUS ROG STRIX Z690-E GAMING WIFI
Intel Core i5-13600K
G.Skill Trident Z5 RGB 32 GB (2 x 16 GB) DDR5-6000 CL36 Memory
ASUS TUF Gaming GeForce RTX 3070 Ti OC V2 Edition 8GB GDDR6X TUF-RTX3070TI-O8G-V2-GAMING
KINGSTON KC3000 1TB PCIe Gen4 NVMe M.2, Read: 7000MB/s; Write: 6000MB/s Solid State Drive
Samsung 870 EVO 4TB SATA III, Read:560 MB/s, Write:530 MB/s Solid State Drive
CORSAIR RMx Series RM1000x 80 PLUS Gold Fully Modular ATX Power Supply
ACER CB282K 4K Monitor

Problem: When monitor is plugged into the motherboard HDMI port, the ASUS Logo/splash screen is displayed on startup and I am able to enter BIOS. When monitor is plugged into the RTX 3070 Ti HDMI port no ASUS Logo/splash screen is displayed on startup, and no amount of hammering on the Del or F2 keys will load the BIOS screen.

BIOS has been updated to 2204 to support 13th Gen CPU, and I have tried setting the BIOS primary graphics setting to PEG, PCIE and CPU without it making any difference. Apart from that, the machine works as expected. Is there any fix for this or am I doomed to having to re-plug in my HDMI cable into the motherboard whenever I want to enter BIOS? Any advice appreciated!

[xarot]

Try disabling fast boot, lengthening the boot splash logo display time, and playing around with CSM settings.

[RMPLP]

@xarot -

Enabling CSM did the trick. It was disabled by default.

Thanks so much for your assistance.

It would be nice if ASUS published detailed instructions for their BIOS settings. Cheers.

[ricardo3200]

I'm with the same problem on a new build.

ASUS ROG STRIX B760-F gaming WiFi

Intel i7 13700f

16gb+16gb memory

Gigabyte Nvidia 1070 GTX (8GB)

No access at all to BIOS probably because the CSM funtion is not enable on BIOS but without access to it is impossible to do the changes.

Worst of it is even to enable the secure boot i need to access BIOS and nothing...

I dont know what to do more to try to access BIOS menu...

[JohnAb]

Can you get hold of another GPU to try? Then you might be able  to access the BIOS, change the settings and then go back to your main GPU.

[JohnAb]

One more idea - I remember that when I used to set CSM on my previous PC, the video output for my two monitors would swap around. So, you might get an output if you try the other ports on you GPU or connect a second monitor.