2U chassis. Up to two 3.33 GHz six-core (3.46 GHz four-core) Intel Xeon 5600 series processors with QuickPath Interconnect technology, up to 1333 MHz memory access speed. Up to 192 GB RDIMMs1 or 48 GB UDIMMs1 high-performance, new-generation DDR-3 memory. Internal storage flexibility with up to 16 2.5" hot-swap SAS/SATA HDDs or SSDs. Up to 4 PCIe slots. Optional 2 GB USB key for virtualization, containing VMware ESXi 4.0 embedded hypervisor. Maximum RDIMM support for 192 GB when 16 GB DIMMs are available in 2Q 2010, and maximum UDIMM support for 48 GB when 4 GB DIMMs are available in 2Q 2010.