The Pentium III brand refers to Intel's 32-bit x86 desktop and mobile microprocessors (with the sixth-generation Intel P6 microarchitecture) introduced on February 26, 1999 and containing 9.5 million transistors. The brand's initial processors were very similar to the earlier CPUs branded Pentium II. The most notable difference was the addition of the SSE instruction set (to accelerate media processing and 3D graphics), and the introduction of a controversial serial number embedded in the chip during the manufacturing process.  Similarly to the Pentium II it superseded, the Pentium III was also accompanied by the Celeron brand for lower-end CPU versions, and the Xeon for high-end (server and workstation) derivatives. The Pentium III was eventually superseded by the Pentium 4, but its Tualatin core also served as the basis for the Pentium M CPUs, which used many ideas from the Intel P6 microarchitecture. Subsequently, it was the P-M microarchitecture of Pentium M branded CPUs, and not the NetBurst found in Pentium 4 processors, that formed the basis for Intel's energy-efficient Intel Core microarchitecture of CPUs branded Core 2, Pentium Dual-Core, Celeron (Core), and Xeon.

                    Pentium III cores

          Katmai

The original version, Katmai (Intel product code 80525), was very similar to the Pentium II (using a 0.25 µm fabrication process), the only differences being the introduction of SSE, and an improved L1 cache controller (which was the cause of the minor performance improvements over the latter PIIs). It was first released at speeds of 450 and 500 MHz. Two more versions were released: 550 MHz on May 17, 1999 and 600 MHz on August 2, 1999. On September 27, 1999 Intel released the 533B and 600B running with 533/600 MHz but using a 133 MHz FSB, all others use a 100 MHz FSB.

          Coppermine

The second version, Coppermine, or 80526, had an integrated full-speed 256-bit 256 KiB L2 cache with lower latency, named Advanced Transfer Cache by Intel, which improved performance significantly over Katmai. Under competitive pressure from AMD’s Athlon processor, Intel also re-worked the chip internally, and finally fixed the well known instruction pipeline stalls. The result was a remarkable 30% increased performance in some applications where these stalls happened.

It was built on a 0.18 μm process. Pentium III Coppermines running at 500, 533, 550, 600, 650, 667, 700, and 733 MHz were first released on October 25, 1999. From December 1999 to May 2000, Intel released Pentium IIIs running at speeds of 750, 800, 850, 866, 900, 933 and 1000 MHz (1 GHz). Both 100 MHz FSB and 133 MHz FSB models were made.

           Coppermine-T

This core was supposed to be an intermediate step between Coppermine and Tualatin, with support for lower-voltage system logic present on the latter but core power within previously defined voltage specs of the former so it could work in older system boards. It existed in Intel's processor roadmap in 2000 but was cancelled on the way to production.

Intel did issue S-Spec production codes (e.g. SL5QK) for some late-model Coppermines that would work with low voltage system bus operation (GTL) at 1.25 V AGTL as well as normal 1.5 V AGTL+ signal levels, and would auto detect differential or single-ended clocking. These processors were probably intended for dual-processor motherboards. However core voltage was the same as other Coppermines.

             Tualatin

The third revision, Tualatin (80530), was a trial for Intel's new 0.13 µm process. Pentium III Tualatins were released during 2001 until early 2002 at speeds of 1.0, 1.13, 1.2, 1.26, 1.33 and 1.4 GHz. Tualatin performed quite well, especially in variations which had 512 KiB L2 cache (called the Pentium III-S). The Pentium III-S variant was mainly intended for servers, especially those where power consumption mattered, i.e., thin blade servers.

Tualatin-based Pentium III CPUs can usually be visually distinguished from Coppermine-based processors by the metal integrated heat-spreader (IHS) fixed on top of the package. However, the very last models of Coppermine Pentium IIIs also featured the IHS - the heatspreader is actually what distinguishes the FC-PGA2 package from the FC-PGA - both are for Socket 370 motherboards.

Pentium 4 branded CPUs introduced the SSE2 and SSE3 instruction sets to accelerate calculations, transactions, media processing, 3D graphics, and games. They also integrated Hyper-Threading (HT), a feature to make one physical CPU working as two logical and virtual CPUs, and more. The Intel's Pentium 4 branded flagship also came in a low-end version branded Celeron (often referred to as Celeron 4), and a high-end derivative branded Xeon intended for servers and workstations. In 2005, the Pentium 4 was superseded by the Pentium D and Pentium Extreme Edition brands of dual-core CPUs.

                     Pentium 4 Processor cores

             Willamette

Willamette, project code name for the first Pentium 4 architecture implementation, experienced long delays in completion of it's design process. The project was started in 1998, when Intel saw the Pentium II as their permanent line. At that time, the Willamette core was expected to operate at frequencies of around 1 GHz, maximum. However, Willamette release delays saw the introduction of the Pentium III prior to it's completion. Since the radical differences in these architectures meant Intel could not market Willamette as a Pentium III, it was named Pentium 4, ending Intel's Roman-numeral nomenclature system.

In November 2000, Intel released the Willamette Pentium 4 at speeds of 1.4 and 1.5 GHz. Most industry experts regarded the initial release as a stopgap product, introduced before it was truly ready. According to these experts, the Willamette was released because the competing AMD Athlon Thunderbird was at that time outperforming the elderly Pentium III, and further improvements to the P-III were not yet possible. The cores were produced using a 0.18 micrometer (180 nm) process and initially used Socket 423 on motherboards, with later revisions moving to Socket 478. These variants were identified by the Intel product codes 80528 and 80531 respectively.

On the test bench, the Willamette was somewhat disappointing to analysts in that not only was it unable to outperform the Athlon and the highest-clocked Pentium IIIs in all testing situations, it was clearly not superior to even the low-end AMD Duron. Although introduced at a price of US$819 (in 1000 unit quantities), it sold at a modest but respectable rate, handicapped somewhat by the requirement of relatively expensive Rambus Dynamic RAM (RDRAM). The Pentium III remained Intel's top selling chip, with the Athlon also selling slightly better than the Pentium 4.

In January 2001, a still slower 1.3 GHz model was added to the range, but over the next twelve months, Intel gradually started reducing AMD's leadership in performance. April 2001 brought the 1.7 GHz P4, the first one to provide performance clearly superior to the old Pentium III. July saw 1.6 and 1.8 GHz models and in August 2001, Intel released 1.9 and 2.0 GHz Pentium 4s. In the same month, they released a new chipset that supported much cheaper PC-133 SDRAM. While SDRAM was much slower than RDRAM, because SDRAM was much cheaper it caused the Pentium 4's sales to grow massively. The new chipset allowed the P4 to displace the Pentium III virtually overnight, becoming the top-selling processor on the market.

The 2.0 GHz P4 was the first to match the performance of the rival AMD Athlon Thunderbird which, until then, had been unquestionably the fastest x86 CPU on the market. Many observers concluded that the Thunderbird was still faster overall, but the performance gap was sufficiently narrow that it was not unreasonable for partisans of either camp to claim superiority. For Intel, this was a very significant achievement. The firm had held the x86 CPU performance crown for nearly 16 years straight, with only two brief exceptions prior to the release of the AMD Athlon.

The Willamette code name is derived from the Willamette River and Willamette Valley region of Oregon, where a large number of Intel manufacturing facilities are located.

               Northwood

In October 2001, the Athlon XP regained a clear lead for AMD, but in January 2002, Intel released Pentium 4s with their new Northwood core at 1.6, 1.8, 2.0 and 2.2 GHz. Northwood (product code 80532) combined an increase in the secondary cache size from 256 KiB to 512 KiB (increasing the transistor count to 55 million, up from 42 million) with a transition to a new 130 nm (0.13 micrometer) fabrication process. By making the chip out of smaller transistors, chips can run at higher clocks or at the same speed while producing less heat. Unfortunately for many consumers, the new core also made upgrades impossible due to the requirement of a new socket (Socket 478), although later adapters were made for Socket 423 to use the Northwood processors.

With Northwood, the P4 came of age. The battle for performance leadership remained competitive (as AMD introduced faster versions of the Athlon XP) but most observers agreed that the fastest Northwood P4 was usually a fraction ahead of its rival.  This was particularly so in the summer of 2002, when AMD's changeover to a 130 nm production process was delayed and the P4s in the 2.4 to 2.8 GHz range were clearly the fastest chips on the market.

A 2.4 GHz P4 was released in April 2002, and the bus speed increased from 400 MT/s to 533 MT/s for a 2.26 GHz, 2.4 GHz, and 2.53 GHz part in May, 2.6 and 2.8 GHz parts in August, and a 3.06 GHz Pentium 4 arrived in November.

The 3.06 GHz processor supported Hyper-Threading (first appeared in Xeon), enabling multiple threads to be run together by duplicating some parts of the processor in order to let the operating system believe that there are two logical processors. HyperThreading was present in all Northwood CPUs, but was disabled in the core in all but the 3.06 GHz model.

In April 2003, Intel launched new 800 MT/s FSB variants, ranging from 2.4 to 3.0 GHz. The key difference on these new versions was that they all supported Hyper-Threading, and ran their system buses at 800 MT/s. This was supposedly to compete better with AMD's Hammer line of processors. However, only Opteron was launched, and motherboard manufactures initially refused to build Opteron-based motherboards with an AGP controller, thus preventing the Opteron from encroaching on the Pentium 4's territory. AMD did boost the Athlon XP's bus speed from 333 MT/s to 400 MT/s, but it wasn't enough to hold off the new 3.0 GHz P4– and the FSB wasn't the problem; the 333 MT/s to 400 MT/s transition yielded little to no performance increase. A 3.2 GHz variant was launched in June and a final 3.4 GHz version was launched in early 2004.

Overclocking early stepping Northwood cores yielded a startling phenomenon. When VCore was increased past 1.7 V, the processor would slowly become more unstable over time, before dying and becoming totally unusable. This is believed to have been caused by the physical phenomenon known as Electromigration, where the internal pathways of the CPU become degraded over time due to excessive electron energy. This was also known as Sudden Northwood Death Syndrome.

              Mobile Pentium 4

The Mobile Intel Pentium 4 Processor  was released to address the problem of putting a full Pentium 4 desktop chip into a laptop, which some manufacturers were doing. The Mobile P4 still used 70 W of power, which let it bridge the gap between the full Pentium 4 (using about 82 W), and the Mobile Pentium 4 M (using about 35 W).

               Mobile Pentium 4 M

Also based on the Northwood core, the Mobile Intel Pentium 4 Processor - M  was released on April 23, 2002  and included Intel's SpeedStep and Deeper Sleep technologies, and Hyper-Threading in some models. Intel's naming conventions made it difficult at the time of the processor's release to identify the processor model.There was the Pentium III mobile chip (or the PIII-M), the Mobile Pentium 4 M (or the P4-M), the Mobile Pentium 4 (or the Mobile P4), and then just the Pentium M which itself was based on the Pentium III.

                Gallatin (Extreme Edition)

In September 2003, at the Intel Developer Forum, the Pentium 4 Extreme Edition (P4EE) was announced, just over a week before the launch of Athlon 64, and Athlon 64 FX (AMD64 FX). The design was mostly identical to Pentium 4 (to the extent that it would run in the same motherboards), but differed by an added 2 MiB of Level 3 cache. It shared the same Gallatin core as the Xeon MP, though in a Socket 478 form factor (as opposed to Socket 603 for the Xeon MP) and with an 800 MT/s bus, twice as fast as that of the Xeon MP. An LGA 775 version is also available.

While Intel maintained that the Extreme Edition was aimed at gamers, some viewed it as an attempt to steal the Athlon 64's launch thunder, nicknaming it the "Emergency Edition". Many condemned Intel for cannibalizing the Xeon line, but because of this, no such complaints were aimed at AMD, who retaliated by doing the same with their Athlon 64 FX.

The effect of the added cache was somewhat variable. In office applications, the Extreme Edition was generally a bit slower than the Northwood, owing to higher latency added by the L3 cache. Some games benefited from the added cache, particularly those based on the Quake III and Unreal engines. However, the area which improved the most was multimedia encoding, which was not only faster than the Pentium 4, but also both Athlon 64s.

A slight performance increase was achieved in late 2004 by increasing the bus speed from 800 MT/s to 1066 MT/s. Only one Gallatin-based chip at 3.46 GHz was released before the Extreme Edition was migrated to the Prescott core. The new 3.73 GHz Extreme Edition had the same features as a 6x0-sequence Prescott 2M, but with a 1066 MT/s bus. In practice however, the 3.73 GHz Extreme Edition almost always proved to be slower than the 3.46 GHz version.

The 'Pentium 4 Extreme Edition' should not be confused with a similarly-named later model, the 'Pentium Extreme Edition', which is based on the dual-core Pentium D.

                Prescott

On February 1, 2004, Intel introduced a new core codenamed "Prescott." The core uses a 90 nm process for the first time, and "[it] is also a major reworking of the Pentium 4's microarchitecture - major enough that some analysts are surprised Intel didn't opt to call this processor the Pentium 5". Although a Prescott clocked at the same rate as a Northwood, benchmarks show that a Northwood performed slightly better than a Prescott in gaming applications. However, with video editing and other multimedia software, the Prescott's extra cache and SSE3 instructions give it a clear clock-for-clock advantage over the Northwood. The Prescott architecture allows it to be easily set at higher clock-rates.  3.8 GHz was the fastest Prescott-based processor ever mass-produced.

Upon release, the Prescott turned out to generate approximately 40% more heat clock-for-clock than the Northwood, and almost every review of it was negative, earning it the soubriquet PresHot. A shift in socket type (from Socket 478 to LGA775) was expected to reduce the heat to more acceptable levels, but in fact proved to have the opposite effect, with power requirements increasing by a further 10%. However, the LGA775 reference cooler and mounting system were somewhat better designs, so average temperatures were slightly lowered. Subsequent revisions to the processor by Intel engineers were expected to reduce average temperatures, but this never happened outside of the lowest speed grades. Prescott Pentium 4s were given the product codes 80546 (Socket 478) and 80547 (LGA775).

Finally, the thermal problems were so severe, Intel decided to abandon the Prescott architecture altogether, and attempts to roll out a 4 GHz part were abandoned, as a waste of internal resources. Also of concern was the fact that a review showed that in games, it took a 5.2 GHz Prescott core to soundly beat the performance of an Athlon FX-55 that clocked at 2.6 GHz. Considering Intel boasted at launch the Pentium 4 architecture was intended to support up to 10 GHz operation, this can be seen as one of the most significant, certainly most public, engineering shortfalls in Intel’s history. This also meant that while Northwood ultimately achieved clockspeeds 70% higher than Willamette did, Prescott only managed a 12% rise over Northwood.

The Pentium M instead became the internal reference layout for Intel’s design teams, and P4 development was essentially abandoned. To this extent, the little-funded Israeli design team that produced the Pentium M core took over the much larger desktop development project.

Why the Prescott ended up in such a disaster can be attributed to internal politics at Intel as much as to poor design. The engineering group was not able to meet the marketing departments desire for ever higher clock speeds, to differentiate their products from AMD. The processor design was not able to clock at the higher speeds required for increased performance and the power consumption was simply untenable. The engineering group kept this information from people in other departments at Intel until it was too late. The termination of the P4 project, when it finally came, had consequences for many members of the management team at the desktop division, but not so much in the engineering or manufacturing groups.

Originally, two Prescott lines were released: the E-series, with an 800 MT/s FSB and Hyper-Threading support, and the low-end A-series, with a 533 MT/s FSB and Hyper-Threading disabled. Initially there were big problems with people who installed Windows XP Service Pack 2 on systems with these processors as an incompatibility with the BIOS, processor and SP2 coding led to systems unable to boot. Microsoft and Intel worked on a solution; Users with this problem can find out how to install SP2 on a Prescott machine.

LGA775 Prescotts use a rating system, labeling them as the 5xx series (Celerons are the 3xx series, while Pentium Ms are the 7xx series). The LGA775 version of the E-series uses model numbers 5x0 (520-560), and the LGA775 version of the A-series uses model numbers 5x5 and 5x9 (505-519). The fastest, the 570J and 571, is clocked at 3.8 GHz. Plans for 4 GHz processors were axed by Intel in favor of dual core processors, although some European retailers claim to be selling a Pentium 4 580, clocked at 4 GHz.

The 5x0J series (and its low-end equivalent, the 5x5J and 5x9J series) introduced the XD Bit (eXecute Disable) or Execute Disabled Bit  to Intel's line of processors. This technology, first introduced to the x86 line by AMD and called NX (No eXecute), can help prevent certain types of malicious code from exploiting a buffer overflow to get executed.

Intel also released a series of Prescotts supporting Intel 64, Intel's implementation of the x86-64 64-bit extensions to the x86 architecture. These were originally released as the F-series, and only sold to OEMs, but they were later renamed to the 5x1 series and sold to the general public. Two low-end Intel64-enabled Prescotts, based on the 5x5/5x9 series, were also released with model numbers 506 and 516.

5x0, 5x0J, and 5x1 series Prescotts have incorporated Hyper-Threading in order to speed up some processes that use multithreaded software, such as video editing. The 5x1 series also supports 64 bit computing.

                Prescott 2M

Intel, by the first quarter of 2005, released a new Prescott core with 6x0 numbering, codenamed "Prescott 2M". It features Intel 64, the XD Bit, EIST (Enhanced Intel SpeedStep Technology), Tm2 (for processors at 3.6GHz and above), and 2 MiB of L2 cache. However, any advantage introduced by the added cache is mostly negated due to higher cache latency, and the double word size if using Intel 64 mode. Rather than being a targeted speed boost the double size cache is intended to provide the same space and hence performance for 64-bit mode operations.

6xx series Prescott 2Ms have incorporated Hyper-Threading in order to speed up some processes that use multithreaded software, such as video editing.

On 14 November 2005, Intel released Prescott 2M processors with VT (Virtualization Technology, codenamed "Vanderpool") enabled. Intel only released two models of this Prescott 2M category: 662 and 672, running at 3.6 and 3.8 GHz, respectively.

               Cedar Mill

By 2005, the NetBurst processors hit a clock speed wall due to a thermal (and power) barrier at 4 GHz, with the Presler reaching a 130 W TDP (a high TDP requires an additional cooling that can be noisy or pricey). The future belonged to more efficient and slower clocked dual-core CPUs on a single die instead of two. The dual die Presler became the last processor branded Pentium D also ending the NetBurst microarchitecture.

A dual-core CPU processes very well with multi-threaded applications (typical for video editing, ray-tracing, rendering, and compressing). Single-threaded applications alone, including games, do not benefit from the second core of a dual-core CPU over an equally clocked single-core CPU. Nevertheless, a dual-core CPU is useful also to run both the client and server processes of a game without noticeable lag in either thread, as each instance could be running on a different core. Furthermore, multi-threaded games benefit from dual-core CPUs.

As of 2006, most business applications and games used only a single thread, which delivered largely the same performance whether run alone on the Pentium D or older Pentium 4 branded CPU at the same clock rate. However, applications rarely run alone on computers under Microsoft Windows, Linux, BSD-family, operating systems. In such multitasking environments, when an antivirus software is running in the background of another program, or where several CPU-intensive applications are running simultaneously, each core of a Pentium D branded processor can handle different program, improving the overall performance over its single-core Pentium 4 counterpart.

Smithfield

Smithfield was the first x86 dual-core microprocessor intended for desktop computers. Intel first launched Smithfield on April 16, 2005 in the form of the 3.2 GHz Hyper-threading enabled Pentium Extreme Edition 840. On May 26, 2005, Intel launched the mainstream Pentium D branded processor lineup with initial clock speeds of 2.8, 3.0, and 3.2 GHz with model numbers of 820, 830, and 840 respectively. In March 2006, Intel launched the last Smithfield processor, the entry-level Pentium D 805, clocked at 2.66 GHz with a 533 MT/s bus. The relatively cheap 805 was found to be highly overclockable; 3.5 GHz was easily achievable and possible just with standard air cooling. Running it at over 4 GHz was possible with water cooling, and at this speed the 805 outperformed the top-of-the-line processors (May 2006) from both major CPU manufacturers (the AMD Athlon 64 FX-60 and Intel Pentium Extreme Edition 965) in many benchmarks.

The 805 and 820 models had a 95 watt TDP. All other models were rated at 130 watts.

All Smithfield processor were made of two 90 nm Prescott cores on a single die with 1 MiB of Level 2 (L2) cache per core. Hyper-threading was disabled in all Pentium D 8xx-series Smithfields but was enabled in the Pentium Extreme Edition 840. Smithfield did not support VT—Intel's virtualization technology formerly called Vanderpool.

All Pentium D processors supported Intel 64 (EM64T), XD Bit, and were manufactured for the LGA775 form factor. The only motherboards guaranteed to work with the Pentium D (and Extreme Edition) branded CPUs were those based on the 945-, 955-, and 975-series Intel chipsets, as well as the nForce 4 SLI Intel Edition and ATI Radeon Xpress. The Pentium D 820 did not work with the nForce 4 SLI Intel Edition chipset due to some power design issues, though they were rectified in the X16 version. The 915- and 925-series chipsets did not work at all with the Smithfields, as they did not support more than one core (to prevent motherboard manufacturers from using them for Xeon branded motherboards, as it happened with the 875P chipset). The 865- and 875-series chipsets supported multiprocessing. Motherboards with them might be Pentium D compatible with an updated BIOS.

A week after its launch, Intel officially denied a report in Computerworld Today Australia that the Pentium D branded CPUs included "secret" digital rights management features their hardware that could be utilized by Microsoft Windows and other operating systems, but was not publicly disclosed. While Intel admitted that there were some DRM technologies in the 945- and 955-series chipsets, it stated that the extent of the technologies was exaggerated, and that the technologies in question had been present in Intel's chipsets since the 875P.

Presler

The newest generation of Pentium D branded processors was the Presler identified by the product code 80553, and made of two 65 nm-process cores found also in Pentium 4 branded Cedar Mill CPUs. The Presler single package also comprised two single-core dice next to each other increasing its processing capability over single-core CPUs branded Pentium 4. The Presler was supported by the same chipsets as the Smithfield. It was produced using 65 nm technology similar to the Yonah. The Presler communicated with the system using an 800 MT/s FSB, and its two cores communicated also using the FSB, just as in the Smithfield. The Presler also included VT (Virtualization Technology, aka Vanderpool, although limited to the 9x0 models, and not in the 9x5 models), Intel 64, XD bit and EIST (Enhanced Intel SpeedStep Technology)[*]. The Presler was released in the first quarter of 2006 with a 2x2 MiB Level 2 cache. Its models included 915, 920, 925, 930, 935, 940, 945, 950, 955, 960 and 965 (with a respective 2.8, 2.8, 3.0, 3,0, 3.2, 3.2, 3.4, 3.4, 3.46, 3.6 and 3.73 GHz clock frequency).

The Presler for models 915, 920, 925, 930, 940, 950 stepping C1, and 915, 925, 935, 945, 950, 960 stepping D0 were rated at a 95 watt TDP. All other models were rated at 130 watts—a 37% increase in power consumption.

[*] – The first batch of Presler processors (revision B1) had the EIST feature turned off by a microcode update because of stability issues. That affected only its power consumption, when idle, and thermal dissipation. Chips with working EIST started shipping in Q2 2006. They had a different S-Spec number which can be found in Intel errata documentation, or at here

Pentium Extreme Edition

Smithfield

Pentium Extreme Edition was introduced at the Spring 2005 Intel Developers Forum, not to be confused with the "Pentium 4 Extreme Edition" (an earlier, single-core processor occupying the same niche). The processor was based on the dual-core Pentium D branded Smithfield, but with Hyper-threading enabled, thus any operating system saw 4 logical processors (2 physical x 2 virtual cores). It also had an unlocked multiplier to allow overclocking. It was initially released as Intel Pentium Extreme Edition 840 at 3.20 GHz, in early 2005, at a price point of $999.99 (OEM version) or $1,200 (Retail). The only chipsets that worked with the Extreme Edition 840 were the Intel's 955X, NVIDIA's nForce4 SLI Intel Edition, and ATi Radeon Xpress 200. Using a Pentium Extreme Edition branded CPU with an Intel 945-series chipset will disable Hyper-threading effectively turning the processor into a Pentium D branded equivalent.

Presler

The Pentium Extreme Edition based on the dual-core Pentium D branded Presler was introduced as the 955 model, at 3.46 GHz, and used a 1066 MT/s FSB compared to the 800 MT/s in the non-extreme edition. A second version, the 965 at 3.73 GHz followed in March 2006. Many overclockers, however, have been able to overclock the core to 4.26 GHz using air cooling simply by raising the unlocked CPU multiplier.

The Presler Extreme Edition would only run combined with the Intel 975X chipset. The i975X featured the ICH7R southbridge and supported all Socket T (LGA775) Pentium 4, Pentium D, and Pentium Extreme Edition branded processors.