Dell Optiplex 990 A20 Bios won't see UEFI USB thumbdrive

[daveydave]

Hi guys, I just bought an Optiplex 990 with the A20 BIOS and it's having trouble seeing my UEFI clover USB stick I made with unibeast. I've been doing these installs for a long time, so I'm thinking it's something with this BIOS (which I've just updated to the latest revision).

I'm using the latest unibeast version and a High Sierra install, selecting UEFI of course.

In the BIOS, I make sure UEFI is selected as well as AHCI mode for the drives. Everything else is the defaults.

It does boot using legacy mode when I created a legacy boot USB, but then can't find my SSD to format, etc from Disk Utility.

Help!

 

[BreBo]

@daveydave, 2nd request - please update your profile (personal details) with your Motherboard, CPU and Graphics Card.
If you have a prebuilt computer enter make and model instead of motherboard (Mobo).

Profiles need to contain at least your primary system to assist others with helping you.

 

[andycruz]

hello i have a dell optiplex 990 small form factor when i go to the bios to change to uefi my boot sequence is blank i need a photo
of the boot sequence that must have.

 

[BreBo]

@andycruz, please update your profile (personal details) with your Motherboard, CPU and iGPU or Graphics Card.
If you have a prebuilt computer enter make and model instead of motherboard (Mobo).

Profiles need to contain at least your primary system to assist others with helping you.