Hello sunbound No, you cannot add another backplane to the server. There are 3 backplane configurations: If you have the 4 drive backplane then the additional slots are designed to be used by a tape and floppy drive. You may have the 6 drive backplane and slots 4 and 5 may just be covered by plastic placeholders. Check to see if the backplane goes all the way across to cover slots 4 and 5. If it does then remove the plastic covers on the front and see if there are connectors for the HDDs. Another way to tell is that the 4 drive backplane is single channel, so it will only use one cable from the RAID controller. Changing out the backplane is not as simple as just swapping them out. It would require a different bezel and several other modifications to make everything fit correctly. I'm not sure if a different chassis would be required, but I wouldn't attempt to swap backplanes. Thanks
 I have a few PE 2950's.   I have both i/5 and i/6 RAID controllers. I notice that they have another, currently unused, port to add another set of drives for (I assume) a backplane for the far right hand side drive bay (4 and 5).  Is there another backplane I can order to utilize this empty bay for hard drives?  I've been looking around, but cannot find anything.   Thanks
6 drives in a 2950