I've noticed since migrating my motherboard from BIOS 49 to BIOS 53 that the USB keyboard or mouse are not recognized during POST when attached to the USB 2 ports on the rear panel (both the black ports and the yellow H/C ports). The practical problem is that i cannot enter BIOS setup, or, if accessing BIOS setup using the "back to BIOS" button, cannot make any changes to the settings.
The keyboard and mouse work normally in regard to BIOS setup if connected to one of the USB 3.0 ports (blue) on the rear panel.
The keyboard and mouse worked as expected with BIOS 43 and 49.
Is there a BIOS setting that might cause this behavior, or is this an error in BIOS 53?
I have the same issue, since updating from bios 49 to 53, my USB keyboard is not recognized during boot/post and I cannot enter the bios unless I get out an old keyboard with a PS2 connection.
My keyboard is connected to the rear USB 2.0 ports, I did not try connecting it to a USB 3.0 port yet. (Thanks for the tip on this!)
In my opinion, after reading that you have the same problem, this is surely a BIOS issue. Like yourself, I had no issue with this with BIOS 49 or any earlier version.
Edit: I also have the DZ77GA-70K