To access the Z-840 BIOS settings you are supposed to hit the ESC key during boot-up. However, if you have a USB keyboard attached, the driver apparently doesn't load until after the boot process has started the OS. I have to dig and old PS2 keyboard out of storage and connect it in order to be able to have an active keyboard during the boot-up.
Supposedly there is a BIOS setting that will allow the USB keyboard to be active during boot-up, but for the life of me I cannot figure out which one it is.