Aorus Z390 Pro, unable to access BIOS

[vulcan]

Aorus Z390 Pro, i9-9900k, RX6800XT

This system was working perfectly until a few days ago when this fault appeard.

i don't know what I've accidentally changed but now I can't access the BIOS using any method but the PC will boot into Win10 and work perfectly.
On startup, and when trying to access the BIOS, instead of the plash screen I briefly get a DOS type prompt to press DEL, pressing DEL does nothing; NB I am using a wired USB keyboard.
Also the VGA LED remains lit.

I am hoping to avoid resetting the CMOS.

Thanks for any help.

[Viv Pyner]

As soon as the computer starts rebooting try pressing the delete key quite rapidly, don't wait for a splash screen. Hopefully this will work. Pressing it once, if that is what you were doing, relies on you guessing correctly when to press it.
Viv

[shadowsports]

Aorus Z390 Pro, i9-9900k, RX6800XT

This system was working perfectly until a few days ago when this fault appeard.

i don't know what I've accidentally changed but now I can't access the BIOS using any method but the PC will boot into Win10 and work perfectly.
On startup, and when trying to access the BIOS, instead of the plash screen I briefly get a DOS type prompt to press DEL, pressing DEL does nothing; NB I am using a wired USB keyboard.
Also the VGA LED remains lit.

I am hoping to avoid resetting the CMOS.

Thanks for any help.

Windows 10...

Settings > Update and Security > Recovery > Advances Start Up (Restart Now) should get you in to the BIOS.

This is often the result of enabling "Fast Boot"

[vulcan]

Thanks for the suggestions however neither of those suggestions work and fast boot is not enabled in windows.

[shadowsports]

Thanks for the suggestions however neither of those suggestions work and fast boot is not enabled in windows.

Greetings,
Fast Boot and Ultra Fast Boot are set in BIOS.  This is a Gigabyte motherboard feature setting, not "Fast Start Up" which is a windows settings.  You can also set Fast and Ultra Fast Boot in Gigabyte Utilities if installed. 

Obviously you have something else keeping you from entering BIOS.  Both of the suggestions provided could work.

Please post a picture of this "Dos type" box you see during start up?  This doesn't sound normal.

Tell us more about your environment.  What type of display are you using?  Onboard video?  Dedicated GPU, any adapters..  and are you outputting to a LCD, TV etc?  The BIOS can only display at standart resolutions, some larger displays don't allow proper scaling which can keep the BIOS from displaying during start up.

[vulcan]

Greetings,
Fast Boot and Ultra Fast Boot are set in BIOS.  This is a Gigabyte motherboard feature setting, not "Fast Start Up" which is a windows settings.  You can also set Fast and Ultra Fast Boot in Gigabyte Utilities if installed. 

Obviously you have something else keeping you from entering BIOS.  Both of the suggestions provided could work.

Please post a picture of this "Dos type" box you see during start up?  This doesn't sound normal.

Attached is a screenshot of the DOS type prompt. The only way I could capture this is from a video because the prompt is only visible for about a second

My RX6800XT is driving a 1080p monitor, a Reverb G1 headset and a 32" TV. These dispalys have been connected for ages and have never caused any issues. There have been no hardware changes between the system working normally and this current issue.
On-board video is disabled in the BIOS, in fact my understanding is the i9-9900k does not support on-board graphics.

[shadowsports]

Greetings,
Thank you, helpful.

The text is not actually a utility or prompt..   this is the normal BIOS information that displays when the >Display Full Screen Logo option is set to [Disabled].  Completely normal.

What happens if you temporarily disconnect the Reverb VR (I have one also  ) and the 32"TV? 

You can try the <DEL> key option or the Avanced start up as mentioned above.

If this doesn't work, I'd use the CLR_CMOS jumper.  A BIOS reset is not a big deal.  It won't take you more than 5 min to re-setup your custom settings.  Let us know how it goes.     

[vulcan]

I reset the CMOS and al is back to normal.

I now realise what I had changed. I had enabled Above 4G decoding to take advantage of AMD's SAM and that's what caused my problems. Needless to say i have left it disabled now.

Thanks for all the helpful replies

[shadowsports]

Good Work!  Glad we could help.