This optional SMP Expansion Module for Xeon MP Models (021870) is installed on the x445 centerplane above the standard module. It is only compatible with the Intel Xeon MP models of the x445. This option must be used to upgrade to 8-way with the Intel Xeon MP 2.0GHz, 2.5 or 2.8GHz processors. Prior to installation, the standard SMP Expansion Module fully populated with four Intel Xeon processors MP of the same type and speed.PRODUCT FEATURES:Sockets for four additional Xeon MP Processors to support XpandOnDemand scalability;64 MB of XceL4 Server Accelerator Cache powers higher performance through decreased latency;Connectors for 16 DIMMs supporting an additional 32GB of system memory for XpandOnDemand memory scalability;Three SMP expansion ports to enable 8-way SMP up to 32-way in the future;IBM XA-32 second generation chipset powering the next generation of breakthrough performance.