Meede85, Please clarify. You purchased R720 with a 2.5" HD backplane but you made an order of 3.5" HD. We do not have adapters for use of 3.5" HDs in the 2.5" HD backplane. However, there are adapters for use of 2.5" HDs in the 3.5" HD backplane. If this is the case, the only option available is to order for the 2.5" HDs. Let me know if you have any further questions.
I got a Power Edge R720 server but ordered a 3.5'' HDD instead of a 2.5".  is there  a way i can use my 3.5" HDD with my Power Edge R720? Anything like an adapter?   
Power Edge HDD compatibility.