In the best of all worlds, I'd like to be able to boot this computer from CD.
This computer doesn't have a CD drive so I have to use an external USB DVD drive. OK.
I have turned off Secure Boot.
Now it allows one to select an "EFI USB Device". This does nothing with a typical live CD.
One CD would be a hard drive test live CD.
Lacking any such live-CD-based HD test capability then how might I test the hard drive - still in the computer?
Related: If I turn off the EFI boot mode then will one still be able to boot from the Windows 8.1 hard drive? Or, will that be lost?