  That is the correct part for the R720. I suspect either the H710 or the integrated storage slot on the system board is faulty. Before replacing parts I would recommend taking the system to minimum-to-POST. Remove or disconnect any unnecessary hardware like the SAS cable on the H710 and see if there is any change. If the H710 still fails to initialize with all other hardware disconnected then you will likely need to start replacing parts. Thanks
Hello,  So I recently acquired a PERC H710 Integrated RAID controller and installed the component as per the Dell documentation here: [URL]        
H710 Controller Not Recognized by BIOS? (PowerEdge R720)