Setting boot on USB in BIOS

I have a fairly new motherboard Asus P5RD1-VM, which I intend to use for Linux and BSD experimental purposes. The machine as a whole works, mostly Puppy, Knoppix and Fedora is run on it. In BIOS it seems there is no option to boot from USB even though there are 6 on-board USB ports. Is there any other way to tell BIOS that booting on USB should be selectable?

Thank you in advance

I too have a newish ASUS mainboard, and although I CAN set it to boot from USB it never actually does, I have found that pressing F8 during POST is the surest way of making it "listen"

F8 at boot gives me the option to boot from USB on my ASUS mobo, as well.

If yours doesn't, look at upgrading the BIOS if there is an upgrade available. Maybe that'll do it.