Thanks for those!
IDE time-out detect was set to 35 (max). I moved it to 0.
IDE busmastering was DISABLED. I left it there.
ACPI High Performance Event was disabled. I enabled it.
No idea what it does, but it sounded promising
Intel VT-d was disabled. I enabled it. Ditto.
No difference on boot, and still no SSD in the Devices list.
Next step is to reverse the first two and see what happens!