The Intel Xeon W3540 was a server/workstation processor with 4 cores, launched in March 2009. It is part of the Xeon lineup, using the Bloomfield architecture with Socket 1366. Thanks to Intel Hyper-Threading the core-count is effectively doubled, to 8 threads. Xeon W3540 has 8 MB of L3 cache and operates at 2.933 GHz by default, but can boost up to 3.2 GHz, depending on the workload. Intel is making the Xeon W3540 on a 45 nm production node using 731 million transistors. The multiplier is locked on Xeon W3540, which limits its overclocking potential.
With a TDP of 130 W, the Xeon W3540 consumes a lot of power, so good cooling is definitely 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 machine, Xeon W3540 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 W3540, which greatly improves virtual machine performance.