I bought a 240GB Transcend M.2 SSD 420S for the free M.2 port of my Lifebook S935.
The disk's interface is SATA III as you can see in the manufacturer's page.
In BIOS, there appear to exist 3 SATA ports. The first belongs to the main hard disk, the second to the DVD bay and the third always looks empty, even after I installed the M.2 SSD.
In the Detailed Specs section of https://www.fujitsu.com/hk/products/computing/pc/ap/notebooks/sseries/s935/ it says the the laptop is even sold with the option of an M.2 SSD.
Any idea why BIOS can't see my SSD?