A:Answer It has ability to boot UEFI mode (default), or Legacy mode, which I have done with Linux, although most modern Linux distros work in UEFI mode, but with secure mode off.
You can get to BIOS settings by tapping F2 or F10 key while it powers up (forget which as I returned it due to dislike of how its low-res screen renders with Linux Mint - but I keep reconsidering as it was not too bad, and this is such a nicely sized PC for me aside from the faintly marked, slippery keys...).