A sort of “shot gun” approach here, obviosly this is not a boot drive, but few things to try…
Make sure that your BIOS also has that SATA port <b>enabled</b>.
Most MB’s have more than one SATA port, try switching to another port.
Make sure that you have the proper SATA drivers for your MB
Right click My Computer
Does it show up there?
Also go into Device manager and select “detect new hardware” and see if it will find it and it will then show up. Check your MotherBoard manufacturer’s guide. You did not say if your first drive is SATA or IDE. Some MB’s support both at the same time, some have connections for both but will only support one or the other.