If you will be install Samsung SSD in mac mini late 2012 (i7), there is some surprise.
You have to swap disks. SSD must be put in HDD place and connected to HDD original SATA cable. HDD going down and have to be connected to accessory cable.
Don't ask me why is that should be done. Only in THIS WAY osx see my SSD (Samsung <- maybe this is the key). I read about this also somewhere on the Internet. My two friends had also this same problem.
ifixit should update their guide