It appears to be the same generation as their main line of 8G servers, which were the first to support USB device booting.
So, assuming it is capable and like the other 8G systems, you will need to insert the USB flash drive first, then power on. Make sure that USB is enabled with BIOS support (in Integrated Devices), THEN check the Boot Sequence for a USB option ... move to the top and make sure it is checked/enabled.