No USB-HDD option in BIOS

For today's computers, the vast majority of motherboards are supported by USB boot, if you find that there is no BIOS inside the USB-HDD option, the key is not set correctly.

The first thing to do is to turn on USB boot device support, such as finding options like "USB Storage Legacy Support" or "USB Storage Function" and setting it to "Enabled."

Next If "USB-HDD" is not found in the startup type, it may be that the BIOS classifies the removable hard drive as a normal hard drive, setting the startup type to "HDD" and then locating the removable hard disk in the specific boot device list (e.g. "Hard disk boot Priority") , and set as the preferred boot device.

It is noteworthy that the different motherboard BIOS options are different, you can find detailed motherboard instructions to follow the set.