If you are installing a H310, i will assume that a storage controller was not sold at point on sale on you were using the S110 embedded controller on the motherboard.  That being the case , the cables installed at the factory went from the SATA ports to the backplane. The installed cables will not work for the H310 as you will now need the cables that goes from the H310 to the backplane. The cable that you need will depend on the R620 hard drive option you have. Please note this cable will probably not be available from Dell but will be available via third parties. Which drive bay option do you have ? Drive bay options:  Up to 4 x 2.5” or  Up to 8 x 2.5” or  Up to 10 x 2.5” 
Hi, I've just installed PERC H310 mini controller to R620 server and can't get HDDs working with it. If I do insert SAS hdds (tried 146, 15k 300Gb 10k and 1Tb 7.2k) I am getting PDR1024 drive mismatch detected error on front display. No hdds listed in RAID controller utility. If I try SATA disk I am not getting PDR error but drive doesn't detected as well. All firmwares updated to latest versions. All drives are original DELL drives. Is it might be because of cables/backplane compatibility (both case preinstalled with server)? Cheers, Alex. 
PDR1024 drive mismatch detected