I have not personally updated my C7H yet - even though I have a 3800X in the box waiting for it. So kudos to you for taking the plunge!
What I can say is from posts on the ROG Crosshair VII overclocking thread at overclock.net - it is not an issue. If I recall correct whats happening there is discrete GPU detection/initialization or boot order detection but I could be 180 out on those. Either way it is not an issue - unless it never gets past that …
thanks for the heads up, I had never messed around that site before, but it looks rather informational so it’s in my bookmarks now!
as for the update, it was relatively easy, I just popped a usb stick in and did the bios update through the easy bios update screen in the bios.
I did not use the bios usb slot, I just used a regular usb slot, but it didn’t seem to matter.
Funny thing is, I only did this update due to stability issues after upgrading to the latest linux kernel (I’m still rocking the 2700). It appears after linux kernel 5.3 I started noticing random lockups and screen freezes, so far so good, but further testing to see if the system is solid now.