Question New monitor glitches when booting, but is fine when in Windows.

[purplehacker]

I just got a brand new 4k monitor (LG UltraGear 27GN950-B), replacing my 1080p monitor, however when I boot my PC it has this weird graphical glitch which goes away when it loads into Windows. However, this makes it very annoying to go into the BIOS as I have to unplug my main monitor and and use my secondary instead. This did not happen before I got a new monitor, and ideas why this could be happening?

Thank you in advance

(It has the typical ROG boot screen but seems to tear and glitch)

 

[PsychoPsyops]

Have you reinstalled your display drivers? This is recommended for any new gpu or monitor swap.
If the issue persists, make sure your display cable is certified and has the necessary bandwidth.
Also, if your BIOS supports UEFI mode, and is not currently in UEFI mode, try that as well. UEFI mode supports more display resolutions than a traditional BIOS does.

 

[purplehacker]

I already reinstalled my display drivers and this display cable has worked fine with everything else, working at 4k 144hz. My BIOS was already in UEFI mode, so i'm not sure what the issue is.

 

[DRagor]

Can you show us pictures how BIOS looks with this glitch? Is it static or the 'noise' moves around the screen? If possible, check in monitor's OSD what parameters (resolution, refresh rates) are set while glitching and how/if they differ from Windows settings.

 

[purplehacker]

Can you show us pictures how BIOS looks with this glitch? Is it static or the 'noise' moves around the screen? If possible, check in monitor's OSD what parameters (resolution, refresh rates) are set while glitching and how/if they differ from Windows settings.

Unfortunetly, as soon as I open the monitor menu when it's glitching in the BIOS, it immedietly closes. Maybe the inputs are messed up?
Bios:

https://imgur.com/a7UzERK

Booting: glitches for a second before booting into windows (I made it so it skips the login prompt)

https://imgur.com/a/YBBnu4D

 

[DRagor]

So if you boot to BIOS you don't see BIOS at all, instead you got those color lines flashing and nothing else, even if you wait?
Do monitor inputs work normal when in Windows?
Can you try this: turn monitor off, boot to Windows, and then turn monitor on. Does the glitch appear in that scenario?
Did you tried using HDMI cable instead? If so does it look any different?