Can't set default boot to USB on Asus P7P55D-E LX motherboard

In Bios, it should give you the option for your USB specifically to boot from.

Try this:

In Bios, go to Advanced, USB Configuration, USB Mass Storage Device Configuration and set Emulation Type to Hard Disk.

Save and exit.

Enter Bios again, and go to Boot/Hard Disk Drives and see if USB Storage Device (it could display the name of the drive for example: Sony thumb drive)is now available in the list. Move it to the first boot slot. Save and exit.

Edit: you should probably have your CD/DVD drive as first, then your USB device after you confirm that the USB device boots up.

Worked for me.

• Using the USB port right next to the Ethernet jack.
• Using a USB Win 10 install (MBR).

BIOS SETTINGS:

• Main>Storage Config>Config Sata (AHCI)
• Advanced>USB Config>USB Functions (Enabled)
• Legacy USB Support (Enabled)
• USB Config>BIOS EHCI Hand-Off (Disabled)
• Advanced>USB Config>USB Mass Storage Dev Config>Emulation Type CDROM
• BOOT>Boot Dev Priority>1st. CD-Rom
• 2nd. USB (Will have the name)

After these have been set Save and exit> Then restart and tap F8 to open the boot menu and select the named USB.

(I only have the setting like this as it worked for me and i was able to boot to the USB, I an unsure of why it worked as some setting maybe wrong)