sate slotThe second M.2 slot usually does run through the chipset, which is also where the SATA controller for ports >5 usually does reside. And sometimes yes using the lower M.2 will disableMost desktop 2.5 drive bays are open-top, open-back and can handle any 2.5 drive, but occasionally you'll find a slot bay desned for one specific heht of drive (usually