I'm using a GA z77x-UD5H and it has its own UEFI dualBios. I am using an external dvd drive to try and install windows 7 because I just built this pc. I have nothing on my HDD yet. All I am trying to do is figure out how to boot using the DVD drive to install windows.
In the list of options to boot from, the dvd drive is not listed. The external Dvd drive is connected through USB, I've tried all the USB ports and it has yet to show on the bootable options. I don't have a preference of UEFI or legacy, I would just like to install windows so I can use my pc.
If you are using the default settings in the bios, the drive should be seen, if it is compatible. But you might check your bios settings to see if there is an entry for it or you may need to change how USB devices are handled during boot. Each bios seems to have different options.
Did you burn the DVD yourself or buy it? How old is the DVD drive?
It sounds like the system is not seeing the External drive. Do you have a flash drive you could plug in to see if it is recognized?
The USB settings in the bios seem to be set correctly with the default settings, so not sure why your drive is not being seen. Does it have its own power source? If it is new, what model?
If you can't get it to work, I would suggest trying to make a bootable flash drive and use it. There are lots of tutorials. I assume you have a computer you can see the DVD with and copy files from it?