page_title: Pentium 4
section_title: Northwood
hierarchical_section_title: Pentium 4 / Processor cores / Northwood
caption_attribution_description: Intel Pentium 4 processor (Northwood 130nm SLASH 2.4 GHz) next to an AMD Athlon XP processor, with a €0.02 Euro Cent piece for scale.
context_page_description: Pentium 4 is a brand by Intel for an entire series of single-core CPUs for desktops, laptops and entry-level servers. The processors were shipped from November 20, 2000, until August 8, 2008. The production of Netburst processors was active from 2000 until May 21, 2010.
  All Pentium 4 CPUs are based on the NetBurst microarchitecture. The Pentium 4 Willamette introduced SSE2, while the Prescott introduced SSE3. Later versions introduced Hyper-Threading Technology.
  The first Pentium 4-branded processor to implement 64-bit was the Prescott, but this feature was not enabled. Intel subsequently began selling 64-bit Pentium 4s using the "E0" revision of the Prescotts, being sold on the OEM market as the Pentium 4, model F. The E0 revision also adds eXecute Disable to Intel 64. Intel's official launch of Intel 64 in mainstream desktop processors was the N0 stepping Prescott-2M.
  Intel also marketed a version of their low-end Celeron processors based on the NetBurst microarchitecture, and a high-end derivative, Xeon, intended for multi-socket servers and workstations. In 2005, the Pentium 4 was complemented by the dual-core-brands Pentium D and Pentium Extreme Edition.
context_section_description: In January 2002, Intel released Pentium 4s with a new core code named "Northwood" at speeds of 1.6 GHz, 1.8 GHz, 2 GHz and 2.2 GHz. Northwood (product code 80532) combined an increase in the L2 cache size from 256 KB to 512 KB (increasing the transistor count from 42 million to 55 million) with a transition to a new 130 nm fabrication process. 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.
  A 2.4 GHz Pentium 4 was released on April 2, 2002, and the bus speed increased from 400 MT/s to 533 MT/s (133 MHz physical clock) for the 2.26 GHz, 2.4 GHz, and 2.53 GHz models in May, 2.66 GHz and 2.8 GHz models in August, and 3.06 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. This was particularly so in mid-2002, when AMD's changeover to its 130 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 GHz range.
  The 3.06 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 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 MT/s FSB (200 MHz physical clock), was clocked at 3 GHz, and had Hyper-Threading technology. This was meant to help the Pentium 4 better compete with AMD's Opteron line of processors. The server-oriented Opteron initially did not share a common socket with AMD's desktop processor line (Socket A). Because of this, motherboard manufacturers did not initially build motherboards with AGP for Opterons. As AGP was the primary graphics expansion port for desktop use, this oversight prevented the Opteron from encroaching from the server market and threatening the Pentium 4 desktop market. Meanwhile, with the launch of the Athlon XP 3200+ in AMD's desktop line, AMD increased the Athlon XP's FSB speed from 333 MT/s to 400 MT/s, but it was not enough to hold off the new 3 GHz Pentium 4 HT. The Pentium 4 HT's increase to a 200 MHz quad-pumped bus (200x4=800Mhz 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, and Intel marketing wisely capitalized on this as a tangible improvement over AMD's desktop processors. Northwood 2.4 GHz, 2.6 GHz and 2.8 GHz variants were released on May 21, 2003. A 3.2 GHz variant was launched on June 23, 2003 and the final 3.4 GHz version arrived on February 2, 2004.
  Overclocking early stepping Northwood cores yielded a startling phenomenon. While core voltage approaching 
caption: A 'Northwood' core Pentium 4 processor. At left is the die (black square in the center), and at right the heat spreader
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