There are many cheap Dell R620s floating around on ebay, and if you can catch one at the right price, it might only have a 4-bay backplane. This is a quick fix, though, unless you have no need for the local storage space.
Personally I just upgraded mine to an 8-bay and decided I would document the steps of what it took.
You will need a few parts. Actually just two.
I originally took photos of the few steps this took, but I cannot seem to find them, so maybe I will upload some photos next time I pull this machine off of the rack.
Installation is fairly simple.
1. First remove any and all drives. Also remove the faceplate cover over the other 4 bays.
- Next disconnect all the components that are connecting to the backplane.
- Pull the blue tabs and pull out the old backplane.
- Remove the old miniSAS cable from the motherboard
- Drop in the new backplane
- Re-connect all the components
- Connect the new mini-SAS cable
That was easy! I hope this helps you.