Xeon


Xeon is a brand of x86 microprocessors designed, manufactured, and marketed by Intel, targeted at the non-consumer workstation, server, and embedded markets. It was introduced on June 29, 1998. Xeon processors are based on the same architecture as regular desktop-grade CPUs, but have advanced features such as support for error correction code memory, higher core counts, more PCI Express lanes, 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 Ultra Path Interconnect bus, which replaced the older QuickPath Interconnect bus.

Branding

The Xeon brand has been maintained over several generations of IA-32 and x86-64 processors. The P6-based models added the Xeon moniker to the end of the name of their corresponding desktop processor, but all models since 2001 used the name Xeon on its own. The Xeon CPUs generally have more cache and cores than their desktop counterparts in addition to multiprocessing capabilities.

Xeon Scalable

The Xeon Scalable brand for high-performance server was introduced in May 2017 with the Skylake-based Xeon Platinum 8100 series. Xeon Scalable processors range from dual socket to 8 socket support. Within the Xeon Scalable brand, there exists the hierarchy of Xeon Bronze, Silver, Gold and Platinum.
In April 2024, Intel announced at its Vision event that the Xeon Scalable brand would be retired, beginning with 6th generation Xeon processors codenamed Sierra Forest and Granite Rapids that will now be referred to as "Xeon 6" processors. This change brings greater emphasis on processor generation numbers.

Xeon 6

With the launch of Intel's Sierra Forest line of processors, branding for mainstream server processors switched to Xeon #, with the # being the generation of the processor, such as Xeon 6 for the 6th generation of Xeon processors, this naming convention also carries over to the Granite Rapids line of server CPUs.
Xeon 6 is split into two product lines, the E series and P series, which, respectively, are all E core and all P core designs. For example, the Xeon 6 6700E line is an all E core based line of processors.

Xeon D

Xeon D is targeted towards microserver and edge computing markets with lower power consumption and integrated I/O blocks such as network interface controllers. This allows Xeon D processors to function as SoCs that do not require a separate southbridge PCH. It was announced in 2014 and the first Xeon D processors were released in March 2015. Xeon D processors come in an soldered BGA package rather than in a socketable form factor. Xeon D was introduced to compete with emerging ARM hyperscale server solutions that offered greater multi-threaded performance and power effiency.
Early 2025, the Xeon 6 SoC line was announced as the 'next gen' for at least a part of the Xeon D lineup.

Xeon W

Xeon W branding is used for Xeon workstation processors. It was first introduced in August 2017 with the release of the Skylake-based Xeon W-2100 series workstation processors. With Sapphire Rapids-WS workstation processors that launched in March 2023, Intel introduced tiers within Xeon W. Xeon w3, w5, w7 and w9 was designed to emulate the Core i3, i5, i7 and i9 branding that Intel had been using for its desktop processors.

Overview

Some shortcomings that make Xeon processors unsuitable for most consumer-grade desktop PCs include lower clock rates at the same price point, and, usually, the lack of an integrated graphics processing unit. Processor models prior to Sapphire Rapids-WS lack support for overclocking. Despite such disadvantages, Xeon processors have always had popularity among some desktop 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.

P6-based Xeon

Pentium II Xeon

The first Xeon-branded processor was the Pentium II Xeon. It was released in 1998, replacing the Pentium Pro in Intel's high-end server lineup. The Pentium II Xeon was a "Deschutes" Pentium II 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 die fabricated in a 0.35 μm four-layer metal CMOS process and packaged in a cavity-down wire-bonded land grid array. The additional cache required a larger module and thus the Pentium II Xeon used a larger slot, Slot 2. It was supported by the i440GX dual-processor workstation chipset and the i450NX quad- or octo-processor server chipset.

Pentium III Xeon

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 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 MT/s front side 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 or octa-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 MT/s, though in practice the cache was able to offset this. The product code for Cascades mirrored that of Coppermine; 80526.

NetBurst-based Xeon

Xeon (DP) and Xeon MP (32-bit)

Foster

In mid-2001, the Xeon brand was introduced. The initial variant that used the new NetBurst microarchitecture, "Foster", was slightly different from the desktop Pentium 4. It was a decent chip for workstations, but for server applications it was almost always outperformed by the older Cascades cores with a 2 MB L2 cache and AMD's Athlon MP. Combined with the need to use expensive Rambus Dynamic RAM, the Foster's sales were somewhat unimpressive.
At most two Foster processors could be accommodated in a symmetric multiprocessing system built with a mainstream chipset, so a second version was introduced with 512 KB or 1 MB L3 cache and the Jackson Hyper-Threading capacity. This improved performance slightly, but not enough to lift it out of third place. It was also priced much higher than the dual-processor versions. The Foster shared the 80528 product code with Willamette.

Prestonia

In 2002, Intel released a 130 nm version of Xeon branded CPU, codenamed "Prestonia". It supported Intel's new Hyper-Threading technology and had a 512 kB L2 cache. This was based on the "Northwood" Pentium 4 core. A new server chipset, E7500, was released to support this processor in servers, and soon the bus speed was boosted to 533 MT/s. The Prestonia performed much better than its predecessor and noticeably better than Athlon MP. The support of new features in the E75xx series also gave it a key advantage over the Pentium III Xeon and Athlon MP branded CPUs, and it quickly became the top-selling server/workstation processor.

Gallatin

Subsequent to the Prestonia was the "Gallatin", which had an L3 cache of 1 MB or 2 MB. Its Xeon MP version, which succeeded Foster MP, was popular in servers. Later experience with the 130 nm process allowed Intel to create the Xeon MP branded Gallatin with 4 MB cache. The Xeon branded Prestonia and Gallatin were designated 80532, like Northwood.

Xeon (DP) and Xeon MP (64-bit)

Nocona and Irwindale

Due to a lack of success with Intel's Itanium and Itanium 2 processors, AMD was able to introduce x86-64, a 64-bit extension to the x86 architecture. Intel followed suit by including Intel 64 in the 90 nm version of the Pentium 4, and a Xeon version codenamed "Nocona" with 1 MB L2 cache was released in 2004. Released with it were the E7525, E7520 and E7320 chipsets, which added support for PCI Express 1.0a, DDR2 and Serial ATA 1.0a. The Xeon was noticeably slower than AMD's Opteron, although it could be faster in situations where Hyper-Threading came into play.
A slightly updated core called "Irwindale" was released in early 2005, with 2 MB L2 cache and the ability to have its clock speed reduced during low processor demand. Although it was a bit more competitive than the Nocona had been, independent showed that AMD's Opteron still outperformed Irwindale. Both of these Prescott-derived Xeons have the product code 80546.