Hello hkmbe,
I understand that you are experiencing problems using the Aivia Osmium* Mechanical Gaming Keyboard to enter BIOS on the Intel(R) Desktop Board DZ77GA-70K.
In regards to the problem that you are experiencing with this keyboard, sometimes we can get there compatibility problems when some complex devices are connected to the motherboard.
I recommend you to o in BIOS and under the SATA configuration enter a hard drive delay, they will halt the system four a couple of seconds to allow the hard drives to initialize, but this will also allow the system to properly recognize your keyboard.
I will also report this issue as it was not reported to us before.
Regards.
PV