Z270WS: Unknown USB Device - Failed enumeration - SOLVED - BIOS BUG??

[moheban79]

Hi,

Spent the better half if not the whole evening trying to solve a problem I had with a mystery usb device that was misbehaving. For starters in Device manager I would get a listing for an Unknown USB Device - In compatibility mode - Failed enumeration error message. I unplugged every device on my motherboard trying to figure this out testing each port and disabling each one one by one. Finally I was about to give up until I noticed my front panel USB 3.1 ports were non functional. I remembered reading that if you set your X4 Pci -e slot to 'X4' mode in bios as I had done some time back that you lose the Asmedia USB 3.1 function only in the front panel. So I wondered if the two events were connected and set my x4 PCI-E slot to 'X2' mode and sure enough the problem went away!

Unbelievable that that was the cause!

[TimeLion724]

You should try reformatting and updating your BIOS, that might be able to fix your USB problems.

[moheban79]

I had just reflashed my bios and not going to reformat my Windows install. Its obviosly a bios bug or something. Sad Asus has stopped providing Bios updates once a board is no longer relevant.