USB boot question

[baoshi]

Well, I just got my hands on the CTO i7/U3 model. Great machine
But u noticed one thing: my USB 3.0 external harddisk refused to boot. Here are the symptoms:
Plug USB 3.0 disk into blue port: power on and press F12, external disk not listed in boot option.
Plug USB 3.0 disk into 2.0 port: power on press F12, it boots normally.
Plug in another USB 2.0 flash drive into blue port, also boots normally.

I'm running bios 1.19, main harddisk in efi mode and bios set to boot "both". UEFI USB bios is enabled.

Any suggestion will be greatly appreciated.