"Paul" wrote

| My newest motherboard, when in UEFI+CSM mode,
| offers *both* legacy and UEFI boot devices in
| the list. In fact, if media is hybrid and supports
| both modes of booting, there are *two* entries
| in the popup boot menu

I have something lik that. The DVD drive can have
up to 3 prepends in the boot menu: UEFI:, P2:, SATA:,
and there can be up to 2 instances, depending on
settings. But there are also instances where it
disappears.
In any case, I didn't know about UEFI/CSM and
no one told me. It took awhile to figure out that
there can be many variations. Many boot disks
won't boot to UEFI. But if it's already UEFI, with
GPT partitioning, then Windows can't install with
it set to CSM. Lots of details. I mention it here
because I expect there are a lot of people who
are not aware of just how quirky the system is.
I'm inclined to re-install to MBR. It's limited
to 2 TB, but I don't expect to be worrying about
that anytime soon. In the meantime it's got much
better general compatibility.