Equallogic PS4000 burning out replacement drives

We've got a PS4000 in our environment which had a drive go bad.  I purchased a replacement drive from a reseller.  The drive was the same make and model, but contained a different firmware on the controller.  I mounted the drive in the drive tray and inserted it, but the array did not recognize it.  I realized there was a jumper on the drive which prevented it from r/w over 1.5 Gb/s.  I removed the jumper and it recognized the drive, BUT the drive burned out within three days and it was only there as a spare so it was not even being actively used in the array.  I chucked it up to bad luck, contacted the reseller, and then sent me out another one.  I placed it in the tray, and what do you know?  Three days later, the drive burned out again.  I'm assuming this has to do with the slot on the appliance, but we're long out of warranty and Dell has specified this model as EoL so I'm basically at a loss here.  I don't want to pull the appliance because I think it's still got some good life left in it, at least for testing and non-critical data, but I'm not sure where to go from here.  Anyone have any ideas?