Xeon
The first Xeon-branded processor was the Pentium II Xeon (code-named "Drake"). It was released in 1998, replacing the Pentium Pro in Intel's server lineup. The Pentium II Xeon was a ""Deschutes"" Pentium II (and shared the same product code: 80523) with a full-speed 512 kB, 1 MB, or 2 MB L2 cache. The L2 cache was implemented with custom 512 kB SRAMs developed by Intel. The number of SRAMs depended on the amount of cache. A 512 kB configuration required one SRAM, a 1 MB configuration: two SRAMs, and a 2 MB configuration: four SRAMs on both sides of the PCB. Each SRAM was a 12.90 mm by 17.23 mm (222.21 mm²) die fabricated in a 0.35 µm four-layer metal CMOS process and packaged in a cavity-down wire-bonded land grid array (LGA). The additional cache required a larger module and thus the Pentium II Xeon used a larger slot, Slot 2. It was supported by the 440GX dual-processor workstation chipset and the 450NX quad- or octo-processor chipset.
Xeon
Introduced in October 2015, Xeon E3-12xx v5 is the first Xeon series based on the Skylake microarchitecture. It uses new LGA 1151 socket, which was introduced with the desktop Core i5/i7 Skylake processors. Although it uses the same socket as consumer processors, it is limited to the C200 server chipset series and will not work with consumer chipsets like Z170. As before, the main difference between the desktop and server versions is added support for ECC memory in the Xeon-branded parts.