Pentium 4

The Pentium 4 brand refers to Intel's line of single-core mainstream desktop and laptop central processing units (CPUs) introduced on November 20, 2000^[1] (August 8, 2008 was the date of last shipments of Pentium 4s^[2]). They had the 7th-generation microarchitecture, called NetBurst, which was the company's first all-new design since 1995, when the Intel P6 microarchitecture of the Pentium Pro CPUs had been introduced. NetBurst differed from the preceding Intel P6 - of Pentium III, II, etc. - by featuring a very deep instruction pipeline to achieve very high clock speeds^[3] (up to 4 GHz) limited only by maximum power consumption (TDP) reaching up to 115 W in 3.6–3.8 GHz Prescotts and Prescotts 2M^[4] (a high TDP requires additional cooling that can be noisy or expensive). In 2004, the initial 32-bit x86 instruction set of the Pentium 4 microprocessors was extended by the 64-bit x86-64 set.

The original Pentium 4, codenamed "Willamette", ran at 1.4 and 1.5 GHz and was released in November 2000 on the Socket 423 platform. Notable with the introduction of the Pentium 4 was the 400 MT/s FSB. It was actually based on a 100 MHz clock wave, but the bus was quad-pumped, meaning that the maximum transfer rate was four times that of a normal bus, so it was considered to run at 400 MT/s. The AMD Athlon was running at 266 MT/s (using a double-pumped bus) at that time.

Pentium 4 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 work as two logical and virtual CPUs. The Intel's flagship Pentium 4 also came in a low-end version branded Celeron (often referred to as Celeron 4), and a high-end derivative, Xeon, intended for multiprocessor servers and workstations. In 2005, the Pentium 4 was complemented by the Pentium D and Pentium Extreme Edition dual-core CPUs.