The Intel Xeon E5520 was a server/workstation processor with 4 cores, launched in March 2009. It is part of the Xeon lineup, using the Gainestown architecture with Socket 1366. Thanks to Intel Hyper-Threading the core-count is effectively doubled, to 8 threads. To further increase overall system performance, up to two Xeon E5520 CPUs can work together in a multi-processor (SMP) configuration. Xeon E5520 has 8 MB of L3 cache and operates at 2.266 GHz by default, but can boost up to 2.533 GHz, depending on the workload. Intel is making the Xeon E5520 on a 45 nm production node using 731 million transistors. The multiplier is locked on Xeon E5520, which limits its overclocking potential.
With a TDP of 80 W, the Xeon E5520 consumes a good deal of power, so decent cooling is needed. Intel's processor supports DDR3 memory with a triple-channel interface. ECC memory is supported, too, which is an important capability for mission-critical systems, to avoid data corruption. For communication with other components in the system, Xeon E5520 uses a PCI-Express Gen 2 connection. This processor lacks integrated graphics, you might need a graphics card.
Hardware virtualization is available on the Xeon E5520, which greatly improves virtual machine performance.