Pentium 4
Intel's NetBurst-based flagship, known for high clock speeds and mixed reviews.
The Pentium 4 is a family of single-core processors from Intel, designed for desktops, laptops, and entry-level servers. These chips shipped from November 20, 2000, to August 8, 2008. Every Pentium 4 used the NetBurst microarchitecture, which replaced the earlier P6 design, and they were Intel’s top-tier processors until 2004, when the Pentium Extreme Edition took the flagship spot, pushing the Pentium 4 to a mid-range role.
The first Pentium 4, codenamed Willamette (built on a 180 nm process), introduced SSE2 instructions. Later, the Prescott version (90 nm) added SSE3 and eventually 64-bit technology, though the initial 64-bit Prescott from February 2004 had this feature disabled. Intel later sold 64-bit Pentium 4s with the "E0" revision, marketed as the Pentium 4, model F, which also included eXecute Disable (Intel’s name for the NX bit) alongside Intel 64. The official mainstream launch of Intel 64 (then called EM64T) came with the N0 stepping Prescott-2M. Hyper-Threading Technology appeared in later versions.
In 2001 and 2002, Intel expanded the Pentium 4 family by introducing the NetBurst-based Celeron line (often called Celeron 4) for budget computers, and the Xeon line for multi-socket servers and workstations. The Pentium Extreme Edition arrived in 2004 as a high-end option, followed by the dual-core Pentium D in 2005. All these were eventually succeeded at the top by the Core 2 brand, though production of the Pentium 4 continued until 2008, when the Pentium Dual-Core replaced it.
The NetBurst microarchitecture had mixed results in benchmarks. With carefully optimized code, early Pentium 4s outperformed Intel’s fastest Pentium III (clocked at 1.13 GHz at the time). However, in legacy applications heavy on branching or x87 floating-point instructions, the Pentium 4 merely matched or ran slower than its predecessor. A key weakness was its shared unidirectional bus. NetBurst also consumed more power and generated more heat than any prior Intel or AMD microarchitecture.
This led to a lukewarm reception. Developers disliked the new optimization rules; for math-heavy tasks, AMD’s lower-clocked Athlon (topping out at 1.2 GHz) easily beat the Pentium 4, which only caught up if software was recompiled with SSE2 support.
Quick Facts
- Arch
- x86 (i386), x86-64 (only some chips)
- Produced-Start
- 2000-11-20
- Produced-End
- 2007-12-07 (orders) / 2008-08-08 (shipments)
- Slowest
- 1.3
- Fastest
- 3.8
- Fsb-Slowest
- 400
- Fsb-Slow-Unit
- MT/s
- Fsb-Fastest
- 1066
- Variant
- Celeron
- Transistors
- 42M 180 nm · 55M 130 nm · 169M 130 nm (P4XE) · 125M 90 nm · 188M 65 nm
- Microarch
- NetBurst
Facts from the source article.
Lore & Background
The Pentium 4's introduction was met with mixed reviews. Developers disliked it due to new code optimization rules; in mathematical applications, AMD's lower-clocked Athlon easily outperformed the Pentium 4, which only caught up if software was recompiled with SSE2 support. Tom Yager of Infoworld magazine called it 'the fastest CPU for programs that fit entirely in cache.' Computer-savvy buyers avoided Pentium 4 PCs due to price premium, questionable benefit, and initial restriction to Rambus' RDRAM. The singular emphasis on clock frequency made it a marketer's dream, leading to the NetBurst microarchitecture being referred to as a 'marketecture' and 'NetBust' by various computing websites and publications.
Reader's Guide
The Pentium 4's significance lies in its embodiment of Intel's strategy to prioritize clock speed over instructions per cycle (IPC), a decision that ultimately proved problematic. While the NetBurst microarchitecture was expected to scale to 10 GHz, it reached a maximum of only 3.8 GHz due to unforeseen transistor power leakage at 90 nm and smaller lithographies. This power leakage, combined with high thermal output, created cooling and clock scaling challenges. Intel attempted core redesigns (notably Prescott) and explored multiple cores, increased FSB speeds, larger caches, and longer pipelines, but these solutions failed. From 2003 to 2005, Intel shifted development to the cooler-running Pentium M microarchitecture, and in January 2006 launched the Core processors emphasizing energy efficiency and performance per clock cycle. The final NetBurst-derived products were released in 2007, with all subsequent families switching to the Core microarchitecture. The Pentium 4's legacy includes its role in popularizing SSE2 and SSE3, introducing Hyper-Threading Technology, and marking a period where Intel's marketing of clock speed was countered by AMD's 'megahertz myth' campaign and PR-rating system.
Did You Know?
- The Pentium 4 Willamette (180 nm) introduced SSE2, while the Prescott (90 nm) introduced SSE3 and later 64-bit technology.
- The first Pentium 4-branded processor to implement 64-bit was the Prescott (90 nm) in February 2004, but this feature was not enabled initially.
- The NetBurst microarchitecture was often called 'NetBust' by reviewers reflecting negatively on its performance.
- Intel bundled two RDRAM modules with each boxed Pentium 4 to facilitate sales.
More in Microprocessors, Part 3 1-24
Spotted an error? Know more?
Reader corrections go straight into our review queue. Suggest an edit · How this site is sourced