Can't boot from USB (GA-Z170M-D3H)

[oRISHi]

Hi. I've recently build a computer for my brother, these are the specs:
Intel Core i5-6400
Gigabyte Z170M-D3H
8GB RAM Gskill Aegis 2400mhz
1TB Western Digital Black

I've updated the BIOS to F7, the last one for this board. The main problem is that it can't boot from any pen drive. I press F12 at startup screen, select my USB device, but then it just shows me the BIOS Boot Manager, like in this picture:

When I select "Boot Manager", the only option that appears is "EFI Hard Drive". At this instance it also should say "EFI USB Device", to boot from the pen drive, but it doesn't. Selecting "EFI Hard Drive" and pressing enter doesn't do anything.

I'm confused because the pen drive is eligible from the BIOS boot options, it displays it's information correctly (name and size), but the Boot manager doesn't allow me to boot from the USB device. I've tried with two different pen drives, that work well on other PCs (I can boot to the installer screen). I've also tried with every USB port on the motherboard, 2.0 and 3.0, and the results are the same.

What should I do?
Thanks in advance.

 

[dexxterlab97]

Which OS are you using?

 

[oRISHi]

I haven't been able to install any OS yet. The installer that's in the pen drive is El Capitan (Mac OSx)

 

[ultimate_1]

Download Rufus

Create a gpt partition scheme for uefi

File system fat 32

Pick iso and create.

Go to bios

Load default and change storage boot contol to uefi only.

Save and exit.

Will now boot from usb.

F7 bios hates legacy.

I have the same board and this worked for me. Don't worry about what usb port you use. I used my front usb 3 port they all work.

If that don't work I bet Ur using a scandisk usb drive. Some scandisk usb drives do not show up as removable storage and will not work with uefi.