2012 Mac mini won't boot from ex-Mac Pro SSD
I have a Mid 2010 Mac Pro as well as a Late 2012 Mac mini.
I recently replaced the Mac Pro's 240 GB OWC SSD with a newer 480 GB OWC SSD. That's all working fine.
The Mac mini just has a single 1 TB internal drive. (It runs Yosemite 10.10.5 for the moment; it's a fresh system with essentially nothing on it.)
I want to transplant the old SSD into the Mac mini. I have it in an external 2.5" USB case momentarily for testing before the transplant.
The SSD has two partitions; one is Mac OS X 10.6.8 and the other is a Windows 7 BootCamp partition.
I can't boot it up into Windows - it BSODs pretty quickly. (Given Windows' finicky nature about precise hardware matching, I'm not surprised.)
But I was surprised to see that it wouldn't boot into 10.6.8. I realize it came from a completely different machine, sure.
I thought if I manually removed the kernel caches (while booted off the 1 TB 10.10.5 internal HDD) and set the boot flags to boot in Safe Mode, it would boot.
Well, it doesn't. It gets through about 10 lines of "..." dots after mentioning "Loading drivers" and then it gets stuck before the end.
I thought a 2012 Mac mini could boot 10.6.8, surely?
I thought removing the kernel caches would let it boot in 'generic' fashion?
Is my only recourse to re-install 10.6.8 - or just say screw it and install a fresh 10.10.5 (I can't go to El Capitan due to it not being mature and some audio drivers that might not work)? I'd prefer to avoid the latter if possible. Maybe I missed some cache file(s) someplace that also needed to be nuked?
Mac mini, OS X Yosemite (10.10.5), Late 2012, 16 GB RAM, 1TB HDD