Xeon
Introduced in May 2013, Xeon E3-12xx v3 is the first Xeon series based on the Haswell microarchitecture. It uses the new LGA 1150 socket, which was introduced with the desktop Core i5/i7 Haswell processors, incompatible with the LGA 1155 that was used in Xeon E3 and E3 v2. As before, the main difference between the desktop and server versions is added support for ECC memory in the Xeon-branded parts. The main benefit of the new microarchitecture is better power efficiency.
Xeon
On May 23, 2006, Intel released the dual-core CPU (Xeon branded 5000 series) codenamed Dempsey (product code 80555). Released as the Dual-Core Xeon 5000-series, Dempsey is a NetBurst microarchitecture processor produced using a 65 nm process, and is virtually identical to Intel's "Presler" Pentium Extreme Edition, except for the addition of SMP support, which lets Dempsey operate in dual-processor systems. Dempsey ranges between 2.50 GHz and 3.73 GHz (model numbers 5020–5080). Some models have a 667 MT/s FSB, and others have a 1066 MT/s FSB. Dempsey has 4 MB of L2 Cache (2 MB per core). A Medium Voltage model, at 3.2 GHz and 1066 MT/s FSB (model number 5063), has also been released. Dempsey also introduces a new interface for Xeon processors: LGA 771, also known as Socket J. Dempsey was the first Xeon core in a long time to be somewhat competitive with its Opteron-based counterparts, although it could not claim a decisive lead in any performance metric – that would have to wait for its successor, the Woodcrest.