This post is all about booting off a USB flash drive on a ASUS P5B motherboard. There are a lot of posts out there for P5B Deluxe but non for just the vanilla P5B. After much looking around in the BIOS I finally found something that worked. ASUS did not make the setting very logical so I figured I would share.
In Order to boot off the USB drive on the P5B you actually have to disable a setting first. This setting on the ASUS P5B is “Quick Boot”. The only thing I can see that Quick Boot actually does is allow you to change the boot up options under “Boot” to “Removable Device”. Once you do this you can now put in a bootable flash drive and boot off of it.
I needed to boot off the Flash drive to install my Windows 2008 Demo box I was making tonight. Worked like a charm!