http://www.asus.com/Motherboards/H87MPRO/#support_Download_35
Here's the link to drivers for your motherboard, go to the BIOS tab and download the latest one.
Refer to this answer in this topic for how to actually update the BIOS:
http://www.tomshardware.com/forum/308518-30-update-bios
I've never updated an ASUS board's BIOS before so I'm not the authority to ask really, which is why I linked the previous link. But I do advice caution in updating this as doing it wrong can come with so unpleasant consequences.