Per the Inspiron 3847 Specifications PDF Storage section =
Internally accessible = Two 3.5-inch drive bay for SATA hard drives (includes hybrid)
The Inspiron 3847 Owner's Manual PDF index list a Primary and Secondary Hard drive.
You can install 2 in the drive bays or 4 if you move to 2.5 inch drives and use an adapter.
MIH81R Great Bear Motherboard has 4 sata connections.