We currently have two 256MB memory DIMM's. Can we upgrade to two 512MB memory DIMM's? We are having a lot of difficulty with upgrades. Our AIP modules are fine and upgrades spike the memory up to 850MB but always settle at 640MB at a stable resting state. This may be a strong indicator that the 4215's do not have enough memory at just 512MB. Please advise as we are having much difficulty with the 4215 sensors.