Processor cores

Processor cores

The Pentium 4 has an IHS (Integrated Heat Spreader) that prevents the die from accidentally getting damaged when mounting and unmounting cooling solutions. Prior to the IHS, a CPU shim was sometimes used by people worried about damaging the core. Overclockers sometimes removed the IHS on Socket 478 chips to allow for more direct heat transfer. However, on LGA775 chips the IHS is directly attached to the die with epoxy, meaning that the IHS cannot be removed easily.
Intel Pentium 4 processor family
Original Logo New Logo Desktop Laptop
Code-named Core Date released Code-named Core Date released
Original Pentium 4 logo New logo as of 2006 Willamette
Northwood
Prescott (180nm)
(130nm)
(90nm) Nov 2000
Jan 2002
Mar 2004 Northwood (130nm) Jun 2003
Pentium 4 logo, M-Variation (P4M) Northwood
Pentium 4-M (130nm) Apr 2002
Hyper-threading (HT)
Original logo for the Intel Pentium 4 with Hyper Threading Technology New Intel Pentium 4 with Hyper Threading logo Northwood
Prescott
Prescott 2M
Cedar Mill (130nm)
(90nm)
(90nm)
(65nm) May 2003
Feb 2004
Feb 2005
Jan 2006 Northwood
Prescott (130nm)
(90nm) Sep 2003
Jun 2004
Pentium 4 HT Extreme Edition logo New logo as of 2006 Gallatin XE
Prescott 2M XE (130nm)
(90nm) Sep 2003
Feb 2005
List of Intel Pentium 4 microprocessors

Willamette
A 'Willamette' core Pentium 4 processor

Willamette, project code name for the first Pentium 4 architecture implementation, experienced long delays in completion of its 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 its completion. Since the radical differences in these architectures meant Intel could not market Willamette as a Pentium III, it was named Pentium 4.

In November 2000, Intel released the Willamette-based 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 Pentium 4 was released because the competing Thunderbird-based AMD Athlon was outperforming the aging Pentium III, and further improvements to the P-III were not yet possible. This Pentium 4 was produced using a 0.18 micrometer (180 nm) process and initially used Socket 423, 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 not clearly superior to even the budget segment's 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 the 845 chipset that supported much cheaper PC133 SDRAM instead of RDRAM. While SDRAM was much slower than RDRAM and severely hampered the bandwidth-hungry Pentium 4, the fact that it was so much cheaper caused the Pentium 4's sales to grow considerably. The new chipset allowed the P4 to displace the Pentium III virtually overnight, becoming the top-selling processor on the market.

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

Northwood
A 'Northwood' core Pentium 4 processor (P4A)

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 KB to 512 KB (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.

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, 2.66 GHz and 2.8 GHz parts in August, and a 3.06 GHz Pentium 4 arrived 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 Northwood P4 was usually ahead of its rival. This was particularly so in the summer of 2002, when AMD's changeover to a 130 nm production process did not help the "Barton" and "Thoroughbred" Athlon XP CPUs clock high enough to overcome the advantage of P4s in the 2.4 to 2.8 GHz range.

The 3.06 GHz processor acquired Hyper-Threading technology that 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.

In April 2003, Intel launched new 800 MT/s FSB variants, ranging from 2.4 to 3.0 GHz. This was meant to help the Pentium 4 better compete with AMD's Opteron line of processors. However, when Opteron was launched, due to its server-oriented positioning motherboard manufacturers didn't initially build motherboards with AGP controllers. Because AGP was the primary graphics expansion port at the time, this missing feature prevented the Opteron from encroaching on the Pentium 4's market segment. 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. A 3.2 GHz Pentium 4 Northwood variant was launched in June and the final 3.4 GHz version arrived in early 2004.

Overclocking early stepping Northwood cores yielded a startling phenomenon. When core voltage (Vcore) was increased past 1.7 V, the processor would slowly become more unstable over time, before dying and becoming totally unusable. This became known as Sudden Northwood Death Syndrome, which is caused by electromigration.