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Pentium D Central processing unit
Produced:	From 2005 to '08[1]
Manufacturer:	Intel
CPU speeds:	2.66 GHz to 3.6 GHz
FSB speeds:	533 MT/s to 800 MT/s
Process: (MOSFET channel length)	0.09 µm to 0.065 µm
Instruction set:	MMX, SSE, SSE2, SSE3, x86-64
Microarchitecture:	NetBurst
Cores:	2 (2x1)
Socket:	LGA 775
Core name:	Smithfield, Presler

The Pentium D^[2] brand refers to two series of dual-core 64-bit x86 processors with the NetBurst microarchitecture. Each CPU comprised two single-core dies (CPUs) - next to each other - in one Multi-Chip Module package. The brand's first processor, codenamed Smithfield, was released by Intel on May 25, 2005. Nine months later, Intel introduced its successor, codenamed Presler^[3], but without offering significant upgrades in design^[4], still resulting in a relatively high power consumption^[5].

By 2005, the NetBurst processors reached the clock speed barrier at 4 GHz due to a thermal (and power) limit exemplified by the Presler's 130 W TDP^[5] (a high TDP requires additional cooling that can be noisy or expensive). The future belonged to more efficient and slower clocked dual-core CPUs on a single die instead of two. The dual die Presler's^[6] last shipment date on August 8, 2008 ^[7] will mark the end of the Pentium D brand and also the NetBurst microarchitecture.

The dual-core CPU runs very well with multi-threaded applications (typical for transcoding audio and video, compressing, photo and video editing and rendering, ray-tracing). The single-threaded applications alone, including games, do not benefit from the second core of dual-core CPU over equally clocked single-core CPU. Nevertheless, the dual-core CPU is useful to run both the client and server processes of a game without noticeable lag in either thread, as each instance could be running on a different core. Furthermore, multi-threaded games benefit from the dual-core CPUs.

As of 2006, most business applications and games used only a single thread. They ran equally, when alone on the Pentium D or older Pentium 4 branded CPUs at the same clock speed. However, the applications rarely run alone on computers under Microsoft Windows, Linux, BSD operating systems. In such multitasking environments, when an antivirus software is running in the background of another program, or where several CPU-intensive applications are running simultaneously, each core of the Pentium D branded processor can handle different programs, improving the overall performance over its single-core Pentium 4 counterpart.

Contents 1 Smithfield 2 Presler 3 Pentium Extreme Edition 3.1 Smithfield 3.2 Presler 4 Successor 5 Implementation 6 See also 7 References 8 External links

Smithfield was the first x86 dual-core microprocessor intended for desktop computers. Intel first launched Smithfield on April 16, 2005 in the form of the 3.2 GHz Hyper-threading enabled Pentium Extreme Edition 840. On May 26, 2005, Intel launched the mainstream Pentium D branded processor lineup with initial clock speeds of 2.8, 3.0, and 3.2 GHz with model numbers of 820, 830, and 840 respectively. In March 2006, Intel launched the last Smithfield processor, the entry-level Pentium D 805, clocked at 2.66 GHz with a 533 MT/s bus. The relatively cheap 805 was found to be highly overclockable; 3.5 GHz was easily achievable and possible just with standard air cooling. Running it at over 4 GHz was possible with water cooling, and at this speed the 805 outperformed the top-of-the-line processors (May 2006) from both major CPU manufacturers (the AMD Athlon 64 FX-60 and Intel Pentium Extreme Edition 965) in many benchmarks.^[8]

The 805 and 820 models had a 95 watt TDP. All other models were rated at 130 watts.

All Smithfield processor were made of two 90 nm Prescott cores on a single die with 1 MiB of Level 2 (L2) cache per core. Hyper-threading was disabled in all Pentium D 8xx-series Smithfields but was enabled in the Pentium Extreme Edition 840. Smithfield did not support VT—Intel's virtualization technology formerly called Vanderpool.

All Pentium D processors supported Intel 64 (EM64T), XD Bit, and were manufactured for the LGA775 form factor. The only motherboards guaranteed to work with the Pentium D (and Extreme Edition) branded CPUs were those based on the 945-, 955-, and 975-series Intel chipsets, as well as the nForce 4 SLI Intel Edition and ATI Radeon Xpress. The Pentium D 820 did not work with the nForce 4 SLI Intel Edition chipset due to some power design issues, though they were rectified in the X16 version. The 915- and 925-series chipsets did not work at all with the Smithfields, as they did not support more than one core (to prevent motherboard manufacturers from using them for Xeon branded motherboards, as it happened with the 875P chipset). The 865- and 875-series chipsets supported multiprocessing. Motherboards with them might be Pentium D compatible with an updated BIOS.

A week after its launch, Intel officially denied a report in Computerworld Today Australia that the Pentium D branded CPUs included "secret" digital rights management features their hardware that could be utilized by Microsoft Windows and other operating systems, but was not publicly disclosed. While Intel admitted that there were some DRM technologies in the 945- and 955-series chipsets, it stated that the extent of the technologies was exaggerated, and that the technologies in question had been present in Intel's chipsets since the 875P.

The newest generation of Pentium D branded processors was the Presler identified by the product code 80553, and made of two 65 nm-process cores found also in Pentium 4 branded Cedar Mill CPUs. The Presler single package also comprised two single-core dies next to each other increasing its processing capability over single-core CPUs branded Pentium 4. The Presler was supported by the same chipsets as the Smithfield. It was produced using 65 nm technology similar to the Yonah. The Presler communicated with the system using an 800 MT/s FSB, and its two cores communicated also using the FSB, just as in the Smithfield. The Presler also included VT (Virtualization Technology, aka Vanderpool, although limited to the 9x0 models, and not in the 9x5 models), Intel 64, XD bit and EIST (Enhanced Intel SpeedStep Technology)[*]. The Presler was released in the first quarter of 2006 with a 2x2 MiB Level 2 cache. Its models included 915, 920, 925, 930, 935, 940, 945, 950, 955, 960 and 965 (with a respective 2.8, 2.8, 3.0, 3,0, 3.2, 3.2, 3.4, 3.4, 3.46, 3.6 and 3.73 GHz clock frequency).

The Presler for models 915, 920, 925, 930, 940, 950 stepping C1, and 915, 925, 935, 945, 950, 960 stepping D0 were rated at a 95 watt TDP. All other models were rated at 130 watts—a 37% increase in power consumption.^[9]

[*] The first batch of Presler processors (revision B1) had the EIST feature turned off by a microcode update because of stability issues. That affected only its power consumption, when idle, and thermal dissipation. Chips with working EIST started shipping in Q2 2006. They had a different S-Spec number which can be found in Intel errata documentation, or here.

Pentium Extreme Edition was introduced at the Spring 2005 Intel Developers Forum, not to be confused with the "Pentium 4 Extreme Edition" (an earlier, single-core processor occupying the same niche). The processor was based on the dual-core Pentium D branded Smithfield, but with Hyper-threading enabled, thus any operating system saw 4 logical processors (2 physical x 2 virtual cores). It also had an unlocked multiplier to allow overclocking. It was initially released as Intel Pentium Extreme Edition 840 at 3.20 GHz, in early 2005, at a price point of $999.99 (OEM version) or $1,200 (Retail). The only chipsets that worked with the Extreme Edition 840 were the Intel's 955X, NVIDIA's nForce4 SLI Intel Edition, and ATi Radeon Xpress 200. Using a Pentium Extreme Edition branded CPU with an Intel 945-series chipset will disable Hyper-threading effectively turning the processor into a Pentium D branded equivalent.

The Pentium Extreme Edition based on the dual-core Pentium D branded Presler was introduced as the 955 model, at 3.46 GHz, and used a 1066 MT/s FSB compared to the 800 MT/s in the non-extreme edition. A second version, the 965 at 3.73 GHz followed in March 2006. Many overclockers, however, have been able to overclock the core to 4.26 GHz using air cooling simply by raising the unlocked CPU multiplier.

The 'Presler Extreme Edition' would run only combined with the Intel 975X chipset. The i975X featured the ICH7R southbridge and supported all Socket T (LGA775) Pentium 4, Pentium D, and Pentium Extreme Edition branded processors.

Main article: Intel Core 2

The Pentium D brand was succeeded on July 27, 2006 by the Core 2 branded line of microprocessors with the Core architecture released as dual- and quad-core CPUs branded Duo, Quad, and Extreme.

In a single-processor scenario, the CPU-to-north bridge link is point-to-point and the only real requirement is that it is fast enough to keep the CPU fed with data from memory.

When assessing the Pentium D, it is important to note that it is essentially two CPUs in the same package and that it will face the same bus contention issues as a pair of Xeons prior to the Dual Independent Bus architecture introduced with the Dual-Core Dempsey Xeons.^{[dubious – discuss]} To use a crude analogy one could say that instead of using a single cable between CPU and north bridge, one must use a Y-splitter. Leaving aside advanced issues such as cache coherency, each core can only use half of the 800 MT/s FSB when under heavy load.

• List of Intel Pentium D microprocessors

• Intel Pentium D Official Website
• Pentium D 800 and 900 Series Review

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