X670/Ryzen - can't get this to work.

[magnayn]

Help! Trying to help a friend build their 1st PC:

* Gigabyte gigabyte x670 aorus elite)
* AMD Ryzen 7 7800X3D 4.2 GHz 8 Core
* G.Skill Trident Z5 Neo RGB 64GB (2 x 32GB) DDR5-6000

Now on a 2nd motherboard, which is also behaviing exactly like the first, in that:

* Fans do not spin at all (neither CPU nor case, which are a mixture of PWM and not)
* Getting into the BIOS is extremely flaky - often pressing <del> does nothing at all.
* Can't get it to boot from a USB stick to install W11 (I know the stick is OK, it's booted in other machines). The BIOS sees the UEFI partition, but it just cycles.
* Can't update the bios (it's F10, tried F30). We managed to get it recognised in the bios Q-Flash, but it hangs/reboots, but the update doesn't take.
* Have tried resetting the CMOS.

At a loss as to what to try next. Seems a bit unlikely that *2* motherboards have the same issue (though the fan thing seems odd). Memory? Any BIOS settings that need to be adjusted?

 

[magnayn]

So to follow up on some of the questions (thanks for the feedback):

* They're 2 completely separate motherboards (Different vendors, 1st one was returned)
* I'm physically there (it's round the corner) and it's been me trying to get into bioses and the like
* Yes, it's minimal (no GPU, just the on-board graphics).

I've built PCs myself, but not for a number of years; Starting to think that unless this particular board is a lemon, it must be one of the other components (though the fan behaviour puzzles me).

Memory? Does that seem likely? It didn't seem to be particularly bleeding-edge for DDR5, but I'm no expert..