The motherboard slot #1 shares bandwidth with a SATA Gb

Compare SSD , mSATA, , SATA Express - m 2 sata slot on motherboard 2 replaces the Mini SATA standard and the Mini PCIe standard Employing a more flexible physical specification, allows different module m2 pcie 40 in 30 slot Yes and its generally written on the manual that which sata ports will be disabled if you are using drive Some motherboards will even

m2 expansion slot 2 supports both SATA and PCIe, an module may only be inserted in either one of the two interfaces, so check your motherboard documentation