|Fingers, don't apologize. You may not be wrong. There are many flavors of IDE/SATA combinations. |
Just as on many boards during the transition from USB 1.1 to USB 2.0 there are many variations or IDE/SATA combinations.
When SATA controllers first appeared they were sometimes configured in pairs to run RAID. However they might not allow you to run a single SATA drive when connected to only one.
I wouldn't be surprised by anything.
I ran into a board in the recent past that had half of the SATA ports that you couldn't boot to. You could only use those ports after you were in an OS. I don't know what that was about.
I was only pointing out that the two types of controllers use different resources.