Sorry to revive this thread but I’m in the exact same situation and could do with some guidance.
sda I have Windows 7 and Ubuntu - both BIOS/MRB I am assuming as there’s no
My plan was to nuke the Ubuntu partitions (
swap) and install Antergos in its place…but I am stuck with the EFI checkbox issue the OP mentions. As some other posters suggest, when booting from the Antergos Live USB I am selecting “UEFI USB” but only because no other option is available (I’ve searched the BIOS for options concerning Legacy)
I also I have an
sdb which I’ve tried to install to install Antergos on and then use BIOS to pick boot but this didn’t work? When I disabled booting from
sda it just told me there was no valid disk to boot from.
Any assistance would be good - losing my Windows install is reaaaallly unappealing