RTX 5080 Dual Monitor won't boot up

[Biker.]

I’m experiencing the same issue on my brand new PC setup:
 

CPU: Ryzen 9 9950X3D

GPU: PNY RTX 5080 OC

Motherboard: ASUS ProArt X870E

RAM: T-Create 32GB x2

Storage: Crucial T700 2TB

PSU: NZXT 1200W
 

Driver version 576.40 didn’t fix the problem.
I’ve already tried several solutions:
 

Used DDU to uninstall and then reinstalled the GPU driver — no luck.
 

Disabled the iGPU — no luck.
 

Enabled CSM in BIOS — this actually worked. Now my computer can cold boot with two monitors connected.
 

My question is:
Should I be concerned about this workaround?
Is this a known RTX 5080 issue, or is it possibly related to my motherboard?
Is there a way to more accurately diagnose the root cause?

[Sawa Takahashi]

6 hours ago, Biker. said:

Enabled CSM in BIOS — this actually worked. Now my computer can cold boot with two monitors connected.
 

My question is:
Should I be concerned about this workaround?

Enabling CSM normally break Secure Boot and prevents Windows 11 from booting. Are you using Windows 10 ?

If your system is working at the moment, I'd pay it no mind. Secure Boot prevents someone who steals your hard drive from booting it in another computer. Most home users do not need that security option.

Have a nice day !

[problemsolver]

20 hours ago, Biker. said:

I’m experiencing the same issue on my brand new PC setup:
 

CPU: Ryzen 9 9950X3D

GPU: PNY RTX 5080 OC

Motherboard: ASUS ProArt X870E

RAM: T-Create 32GB x2

Storage: Crucial T700 2TB

PSU: NZXT 1200W
 

Driver version 576.40 didn’t fix the problem.
I’ve already tried several solutions:
 

Used DDU to uninstall and then reinstalled the GPU driver — no luck.
 

Disabled the iGPU — no luck.
 

Enabled CSM in BIOS — this actually worked. Now my computer can cold boot with two monitors connected.
 

My question is:
Should I be concerned about this workaround?
Is this a known RTX 5080 issue, or is it possibly related to my motherboard?
Is there a way to more accurately diagnose the root cause?

Do you have the latest UEFI (BIOS) update for your motherboard? That is the first thing I would update to address this issue.
You also don't have the latest NVidia driver: 576.52 as of today (the day you posted), so please install that too
- You need CSM disabled for Re-Sizeable BAR to be enabled, which you definitely want enabled if you play games
- Despite some embarrassing flaws recently, you also want Secure Boot enabled for many different security reasons. It can prevent entire classes of malware including bootkits and rootkits, which very much apply to home users, or any user.