I want to install Fedora 15 from a USB drive, which I prepared with UNetbootin.

The official documentation says:

Insert the memory key into a USB port and restart the computer.
When F12 = Boot Menu appears in the upper-right corner of the screen, press <F12>.

I plug it into my Dell Optiplex 755, but from the Boot menu, there's no option to boot from the USB drive. So I go into BIOS, and find that in "Boot Sequence", the USB Device option is "not present".

enter image description here

Here's some additional info:

  • BIOS version: A08 (02/19/08)
  • Core 2 Duo E6550 CPU
  • USB Drive formatted as FAT-32 using the Fedora 15 ISO file
  • Branded system often limit BIOS options. The two-year-old Acer notebook I use at work has almost no BIOS options at all where as the BIOS of the desktop I built 10 years ago has lots.
    – Synetech
    Aug 8, 2013 at 1:44
  • It appears that you can only USB boot from the front USB ports. I tried it in the back and had the same issue.
    – user245359
    Aug 13, 2013 at 15:31
  • Also make sure you have no other USB drive plugged into a USB port or the computer will just sit there and do nothing. You can only have one device plugged in at boot up it seems.
    – user403974
    Jan 2, 2015 at 19:54

3 Answers 3


Go to the BIOS and look for Onboard Devices » USB Controller. While the default setting here is On, in this case it could be No Boot.

enter image description here

Change it back to On, restart, and you should be able to boot from the USB device.

  • 2
    If it helps, in my Bios setup, I also had to disable Secure Boot and enable Legacy boot options before USB was an option.
    – Ryan
    Jun 9, 2015 at 18:39
  • Thanks @Ryan: too bad this comment wasn't added as an answer, as <Disable Secure Boot> and <Enable Legacy Boot ROMs> worked for me on an Optiplex 9020.
    – MTAdmin
    Jun 22, 2016 at 20:53

In the Optiplex 755 BIOS, you need to not only set the boot order in "Boot Sequence" but you also need to make sure the device you want to boot from has a number to the left of it. If you don't see a number, it's not enabled to boot and you need to hit the space bar with it selected. Then a number will show up and you can use "U" and "D" to go up and down with your boot order (usually moving the one you want to boot to the very top).


In the case of a GX620, "USB Storage Device" is not a boot option.
Further,the meaning of "USB Device" defined therein does NOT include a flash drive.
It includes a "memory key" and devices connected to USB ports.
When all else fails, read your Optiplex manual.

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