When you say "BIOS", do you mean the traditional BIOS Setup (F2), or do you mean the controller BIOS for the onboard CERC SATA 1.5/2s controller?  You should not be able to see the disk in F2 ... if necessary/possible, simply enable SATA port 1 in F2 (and save), then boot to CTRL-A to see the disk.  If it will not allow you to enable port 1, then check the data and power cables on the new disk you added - even test it in another machine to make sure it works.
I am trying to add a second 500GB SATA drive to my PowerEdge 850. When I go to the BIOS and try to enable but nothing happens. Is there something else I am supposed to do?
Adding SATA drive to port 1 does not show in BIOS