You can refer below link for various backplane connectivity supported by T620. If you refer below link you can observed that you can not connect backplane to both Software RAID and RAID controller same time. Only one supported at a time. [URL]  
I have a T620 PowerEdge server with a PERC S110.  I noticed that PERC S110 is a software based, so am thinking of migrating to PERC H710.  Currently, a RAID 5 array of 4 SATA hard disk drives is implemented using S110. The boot/OS partition is on the RAID array.  Performance is not good, and I am not happy that these drives are SATA drives, and the maximum number of disks you can connect to S110 is 4. Can I install PERC H710 on the same T620 server with PERC S110?  That is, can the T620 server have two PERCs, and will those PERCs operate normally without conflict? What I am thinking of doing is installing H710 additionally in the same T620 server with S110, and creating a RAID 5 array of 4 SAS hard disk drives using H710.  So, this T620 server will have one RAID 5 array implemented by S110, and another RAID 5 array implemented by H710.  Then, I will use a disk cloning software (which works inside the Windows) to clone the partitions from the RAID 5 array of S110 to the RAID 5 array of H710.  After that, I will remove S110 from the system.   Will this scenario work?  Has anyone tried this?  Or, is there a better way?  Thanks in advance.
Multiple RAID controllers in a system