Cheers mate.
Certainly you have the Z board.
Now go to the ASUS support page for the CHV-z board and download the latest bios, or the bios version you want to have on your system.
Extract the bios to the root directory of a fat formatted USB stick, place the stick in a USB2 port and get into bios, use the EZflash2 utility in the tools menu of the bios and flash your board.
To help us help you - please provide as much information about your system and the problem as possible.