I have a Gigabyte Z390 AORUS with a 9900k.
 
After I installed the 3080 FTW3 Ultra and booted up, the motherboard/BIOS beeped 4-5 times instead of a A0 State (one beep).
What causes this is simple.  Look for "CSM Support" in the BIOS.  If you disable "CSM Support" in the BIOS, your motherboard/BIOS should beep just once.
 
This worked for me.  Mileage may vary.

Try the Gigabyte forum this is for EVGA users
 

veganfanatic
Try the Gigabyte forum this is for EVGA users
 

His card is EVGA.  I will follow this thread as my 3080 FTW3 Ultra is on its way to me.

I get 4 extra beeps from the 3090 FTW3 Ultra, but I cannot change CSM settings with my add in RAID card. (Windows won't boot if I do)

veganfanatic
Try the Gigabyte forum this is for EVGA users
 

Sorry-->  After I installed the EVGA 3080 FTW3 Ultra and booted up...
 
I'm just trying to help others.

I think I already disabled this beforehand but thanks for the tip anyways!

I'm having the same issue as you with a 3090 FTW3. Same MB and CPU. Get 4 quick beeps than the normal beep. Machine runs fine after booting, but the 4 beeps is driving me crazy.

turning off CSM solved the 4 beep issue for me too....
 

I'm glad this post helped. 

Turning off CSM did fix the beeping issue, but then windows won't load up. I'll keep playing around with it
 
Edit: had to convert my boot drive to GPT. I can disable CSM now and everything working fine. Thanks for the fix