The IBM Power Systems 520 Express server is designed to bring the economies, efficiencies, and capabilities of POWER6 to your small and distributed business needs.
Summary of standard features:

-Tower or rack-mount (4U) configurations

-1-, 2-, and 4-core SMP design

-1 GB of PC2-5300 667 MHz ECC (error checking and correcting) memory expandable to 16 GB (1-core), 32 GB (2-core), or 64 GB (4-core)

-Choice of three DASD options:
 -6 x 3.5-inch DASD backplane with no external SAS port
 -6 x 3.5-inch DASD backplane with an external SAS port
 -8 x 2.5-inch DASD backplane with an external SAS port

-Choice of three integrated virtual Ethernet daughter cards:
 -Dual-port 10/100/1000 Mb copper(default)
 -Quad-port 10/100/1000 Mb copper
 -Dual-port 10 Gb optical

-Two media bays:
 -One slim bay for an IDE or SATA DVD-ROM (optional) or DVD-RAM (optional)
 -One half-high bay for a tape drive (optional)

-A maximum of five hot-swap slots:
 -Two PCIe x8 slot, short card length
 -One PCIe x8 slots, full card length
 -Two PCIX DDR slots, full card length

-One GX+ slot (shares same space as PCIe x8 slot 1) (GX+ slot not available on a 1-core configuration)
 -One GX++ slot (unshared) (available only on a 4-core configuration)

-One Power Supply, 950 Watt AC, Hot-swap, Base (redundant power optional)

 -Service Processor FSP-1
 -SAS/SATA controller
 -Dual-port 10/100/1000 Mb Ethernet
  +Optional Quad-port 10/100/1000 Mb Ethernet
  +Optional Dual-port 10 Gigabit Ethernet

-Hot-swap and redundant cooling
-Three USB ports; two system ports
-Two HMC ports; two SPCN ports