Editing Pentium 4 (section)

===Northwood===<!-- This section is linked from [[Celeron]] -->
[[File:Pentium 4 Northwood SL6SH.jpg|right|thumb|180px|A 'Northwood' core Pentium 4 processor. At left is the [[Die (integrated circuit)|die]] (black square in the center), and at right the [[heat spreader]].]]
[[File:Intel@130nm@NetBurst@Northwood@Pentium4@SL6PF DSC07596 (32847415126).jpg|thumb|Die shot of a Northwood Pentium 4]]
In January 2002, Intel released Pentium 4s with a new core codenamed Northwood at speeds of 1.6&nbsp;GHz, 1.8&nbsp;GHz, 2&nbsp;GHz and 2.2&nbsp;GHz.<ref>Wasson, Scott. [http://techreport.com/articles.x/2975/1 AMD's Athlon XP 1800+ processor], Tech Report, October 9, 2001.</ref><ref name=TRP4Northwood22>Wasson, Scott and Brown, Andrew. [http://techreport.com/articles.x/3289 Pentium 4 'Northwood' 2.2 GHz vs. Athlon XP 2000+], January 7, 2002.</ref> Northwood (product code 80532) combined an increase in the [[L2 cache]] size from 256&nbsp;KB to 512&nbsp;KB (increasing the transistor count from 42 million to 55 million) with a transition to a new [[130 nm]] fabrication process.<ref name=TRP4Northwood22 /> Making the processor out of smaller transistors means that it can run at higher clock speeds and produce less heat. In the same month boards utilizing the 845 chipset were released with enabled support for [[DDR SDRAM]] which provided double the bandwidth of PC133 SDRAM, and alleviated the associated high costs of using Rambus RDRAM for maximal performance with Pentium 4.{{Citation needed|date=April 2011}}

A 2.4&nbsp;GHz Pentium 4 was released on April 2, 2002, and the bus speed increased from 400&nbsp;[[Transfer (computing)|MT/s]] to 533&nbsp;MT/s (133&nbsp;MHz physical clock) for the 2.26&nbsp;GHz, 2.4&nbsp;GHz, and 2.53&nbsp;GHz models in May, 2.66&nbsp;GHz and 2.8&nbsp;GHz models in August, and 3.06&nbsp;GHz model in November. With Northwood, the Pentium 4 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-clocked Northwood-based Pentium 4 was usually ahead of its rival.{{Citation needed|date=April 2011}} This was particularly so in mid-2002, when AMD's changeover to its 130&nbsp;nm production process did not help the initial "Thoroughbred A" revision Athlon XP CPUs to clock high enough to overcome the advantages of Northwood in the 2.4 to 2.8&nbsp;GHz range.<ref>Wasson, Scott. [http://techreport.com/articles.x/4163 AMD's Athlon XP 2800+ and NVIDIA's nForce2], Tech Report, October 1, 2002.</ref>

The 3.06&nbsp;GHz Pentium 4 enabled [[Hyper-Threading]] Technology that was first supported in Foster-based Xeons. This began the convention of virtual processors (or virtual cores) under x86 by enabling multiple threads to be run at the same time on the same physical processor. By shuffling two (ideally differing) program instructions to simultaneously execute through a single physical processor core, the goal is to best utilize processor resources that would have otherwise been unused from the traditional approach of having these single instructions wait for each other to execute singularly through the core. This initial 3.06&nbsp;GHz 533FSB Pentium 4 Hyper-Threading enabled processor was known as Pentium 4 HT and was introduced to mass market by Gateway in November 2002.

On April 14, 2003, Intel officially launched the new Pentium 4 HT processor. This processor used an 800&nbsp;MT/s FSB (200&nbsp;MHz physical clock), was clocked at 3&nbsp;GHz, and had Hyper-Threading technology.<ref>Wasson, Scott. [http://techreport.com/articles.x/5292 Intel's Pentium 4 3.2 GHz processor], Tech Report, June 23, 2003.</ref> This was meant to help the Pentium 4 better compete with AMD's [[Opteron]] line of processors. Meanwhile, with the launch of the Athlon XP 3200+ in AMD's desktop line, AMD increased the Athlon XP's FSB speed from 333&nbsp;MT/s to 400&nbsp;MT/s, but it was not enough to hold off the new 3&nbsp;GHz Pentium 4 HT.<ref>Wasson, Scott. [http://techreport.com/articles.x/5126 AMD's Athlon XP 3200+ processor], Tech Report, May 13, 2003.</ref> 

The Pentium 4 HT's increase to a 200&nbsp;MHz quad-pumped bus (200&nbsp;x 4 = 800&nbsp;MHz effective) greatly helped to satisfy the bandwidth requirements the NetBurst architecture desired for reaching optimal performance. While the Athlon XP architecture was less dependent on bandwidth, the bandwidth numbers reached by Intel were well out of range for the Athlon's EV6 bus. Hypothetically, EV6 could have achieved the same bandwidth numbers, but only at speeds unreachable at the time. Intel's higher bandwidth proved useful in benchmarks for streaming operations{{Citation needed|date=April 2011}}, and Intel marketing wisely capitalized on this as a tangible improvement over AMD's desktop processors{{Citation needed|date=April 2011}}. Northwood 2.4&nbsp;GHz, 2.6&nbsp;GHz and 2.8&nbsp;GHz variants were released on May 21, 2003. A 3.2&nbsp;GHz variant was launched on June 23, 2003 and the final 3.4&nbsp;GHz version arrived on February 2, 2004.

Overclocking early stepping Northwood cores yielded a startling phenomenon. While core voltage approaching 1.7 V and above would often allow substantial additional gains in overclocking headroom, the processor would slowly (over several months or even weeks) become more unstable over time with a degradation in maximum stable clock speed before dying and becoming totally unusable. This became known as ''Sudden Northwood Death Syndrome'' (SNDS), which was caused by [[electromigration]].<ref>Shilov, Anton. [http://www.xbitlabs.com/news/cpu/display/news6375.html Sudden Overclocked Northwood Death Syndrome. Is It Strange That Overclocked CPUs Eventually Die?] {{webarchive|url=https://web.archive.org/web/20071231130915/http://www.xbitlabs.com/news/cpu/display/news6375.html |date=2007-12-31 }}, X-bit Labs, December 6, 2002.</ref>

====Pentium 4 M====
Also based on the Northwood core, the ''Mobile Intel Pentium 4 Processor - M''<ref>{{cite web |url=http://www.intel.com/design/mobile/datashts/250686.htm |title=Mobile Intel Pentium 4 Processor-M Datasheet |publisher=Intel Corp}}</ref> (also known as the ''Pentium 4 M'') was released on April 23, 2002, and included Intel's [[SpeedStep]] and Deeper Sleep technologies. Its [[Thermal design power|TDP]] is about 35 watts in most applications. This lowered power consumption was due to lowered core voltage, and other features mentioned previously.

Unlike the desktop Pentium 4, the Pentium 4 M did not feature an integrated heat spreader (IHS), and it operates at a lower voltage. The lower voltage means lower power consumption, and in turn less heat. However, according to Intel specifications, the Pentium 4 M had a maximum thermal [[junction temperature]] rating of 100 degrees C, approximately 40 degrees higher than the desktop Pentium 4.

====Mobile Pentium 4====
The ''Mobile Intel Pentium 4 Processor''<ref>{{cite web |url=http://www.intel.com/products/processor/mobilepentium4/index.htm |title=Intel's Mobile Pentium 4 |publisher=Intel Corp}}</ref> was released to address the problem of putting a full desktop Pentium 4 processor into a laptop, which some manufacturers were doing{{cn|date=April 2023}}. The Mobile Pentium 4 used a 533&nbsp;MT/s FSB, following the desktop Pentium 4's evolution. Oddly, increasing the bus speed by 133&nbsp;MT/s (33&nbsp;MHz) caused a massive increase in TDPs, as mobile Pentium 4 processors emitted 59.8–70&nbsp;W of heat, with the Hyper-Threading variants emitting 66.1–88&nbsp;W. This allowed the mobile Pentium 4 to bridge the gap between the desktop Pentium 4 (up to 115&nbsp;W TDP), and the Pentium 4 M (up to 35&nbsp;W TDP).

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, the Pentium 4 M, the Mobile Pentium 4, and then the [[Pentium M]], which itself was based on the Pentium III and was significantly faster and more power-efficient than the former three.