Xeon

Xeon (/ˈziːɒn/ ZEE-on) is a brand of x86 microprocessors designed, manufactured, and marketed by Intel, targeted at the non-consumer workstation, server, and embedded system markets. It was introduced in June 1998. Xeon processors are based on the same architecture as regular desktop-grade CPUs, but have some advanced features such as support for ECC memory, higher core counts, support for larger amounts of RAM, larger cache memory and extra provision for enterprise-grade reliability, availability and serviceability features responsible for handling hardware exceptions through the Machine Check Architecture. They are often capable of safely continuing execution where a normal processor cannot due to these extra RAS features, depending on the type and severity of the Machine Check Exception. Some also support multi-socket systems with two, four, or eight sockets through use of the Quick Path Interconnect bus. Some shortcomings that make Xeon processors unsuitable for most consumer-grade desktop PCs include lower clock rates at the same price point (since servers run more tasks in parallel than desktops, core counts are more important than clock rates), usually an absence of an integrated GPU, and lack of support for overclocking. Despite such disadvantages, Xeon processors have always had popularity among some desktop users (video editors and other power users), mainly due to higher core count potential, and higher performance to price ratio vs. the Core i7 in terms of total computing power of all cores. Since most Intel Xeon CPUs lack an integrated GPU, systems built with those processors require a discrete graphics card or a separate GPU if computer monitor output is desired. Intel Xeon is a distinct product line from the similarly-named Intel Xeon Phi. The first-generation Xeon Phi is a completely different type of device more comparable to a graphics card; it is designed for a PCI Express slot and is meant to be used as a multi-core coprocessor, like the Nvidia Tesla. In the second generation, Xeon Phi evolved into a main processor more similar to the Xeon. It conforms to the same socket as a Xeon processor and is x86-compatible; however, as compared to Xeon, the design point of the Xeon Phi emphasizes more cores with higher memory bandwidth. The Xeon brand has been maintained over several generations of IA-32 and x86-64 processors. Older models added the Xeon moniker to the end of the name of their corresponding desktop processor, but more recent models used the name Xeon on its own. The Xeon CPUs generally have more cache than their desktop counterparts in addition to multiprocessing capabilities. 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. In 1999, the Pentium II Xeon was replaced by the Pentium III Xeon. Reflecting the incremental changes from the Pentium II 'Deschutes' core to the Pentium III 'Katmai' core, the first Pentium III Xeon, named 'Tanner', was just like its predecessor except for the addition of Streaming SIMD Extensions (SSE) and a few cache controller improvements. The product codes for Tanner mirrored that of Katmai; 80525. The second version, named 'Cascades', was based on the Pentium III 'Coppermine' core. The 'Cascades' Xeon used a 133 MHz bus and relatively small 256 kB on-die L2 cache resulting in almost the same capabilities as the Slot 1 Coppermine processors, which were capable of dual-processor operation but not quad-processor operation. To improve this situation, Intel released another version, officially also named 'Cascades', but often referred to as 'Cascades 2 MB'. That came in two variants: with 1 MB or 2 MB of L2 cache. Its bus speed was fixed at 100 MHz, though in practice the cache was able to offset this. The product code for Cascades mirrored that of Coppermine; 80526.