Sorry for the delay Shane.   That is correct, the H310 for the R720 is the Mini mono (part number K09CJ). The HV52W  looks to be the desktop version.  
I have an r720 with h310 controller.  I have a MX3P7 cable plugged into the motherboard and backplane.  I have tried several (DELL) drives and none of them show up in the controller bios.  The server sees the card but the controller doesn't see the drives.  The system recognizes when the drives are inserted/removed (i get an orange light with a warning that a drive was removed when I remove one).   I would be most grateful for any ideas on what I might be doing wrong.  Thanks!
h310 and r720