Pentium D

Pentium D

Produced	From 2005 to 2008[1]
Common manufacturer(s)	Intel
Max. CPU clock	2.66 GHz to 3.73 GHz
FSB speeds	533 MT/s to 1066 MT/s
Min. feature size	90 nm to 65 nm
Instruction set	MMX, SSE, SSE2, SSE3, x86-64
Microarchitecture	NetBurst
Cores	2 (2x1)
Socket(s)	LGA 775
Core name(s)	Smithfield, Presler

The Pentium D^[2] brand refers to two series of desktop dual-core 64-bit x86 processors with the NetBurst microarchitecture manufactured by Intel. Each CPU comprised two dies, each containing a single core residing next to each other on a 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 2004, the NetBurst processors reached a clock speed barrier at 3.8 GHz due to a thermal (and power) limit exemplified by the Presler's 130 W Thermal Design Power^[5] (a higher TDP requires additional cooling that can be prohibitively noisy or expensive). The future belonged to more energy efficient and slower clocked dual-core CPUs on a single die instead of two.^[6] The final shipment date of the dual die Presler chips was August 8, 2008,^[7] which marked the end of the Pentium D brand and also the NetBurst microarchitecture.

Pentium D/Extreme Edition

The dual-core CPU is capable of running multi-threaded applications typical in transcoding of audio and video, compressing, photo and video editing and rendering, and ray-tracing. Single-threaded applications alone, including most games, do not benefit from the second core of dual-core CPU compared to 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 2008 many business applications are optimized for multiple cores. They run at similar speed when not multitasking on the Pentium D or older Pentium 4 branded CPUs at the same clock speed. However, in multitasking environments such as Microsoft Windows, Linux, BSD operating systems, other processes are often running at the same time; if they require significant CPU time, each core of the Pentium D branded processor can handle different programs, improving overall processing speed over its single-core Pentium 4 counterpart.

Intel Pentium D processor family
Original Logo	New Logo	Desktop
		Code-named	Core	Date released
		Smithfield Presler	(90nm) (65nm)	May 2005 Jan 2006
		Smithfield XE Presler XE	(90nm) (65nm)	May 2005 Jan 2006
List of Intel Pentium D microprocessors

Smithfield

Underside of a Pentium D 820

Smithfield was the first x86 dual-core microprocessor intended for desktop computers^{[citation needed]}. 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 often possible with good 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 including power consumption.^[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, each one on its own die with 1 MB 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 Intel VT—Intel's x86 virtualization (formerly Vanderpool).

All Pentium D processors supported Intel 64 (formerly EM64T), XD Bit, and were manufactured for the LGA 775 form factor. The only motherboards guaranteed to work with the Pentium D (and Extreme Edition) branded CPUs were those based on the 945-, 955-, 965- 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 had 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 ^[9] in Computerworld Today Australia that the Pentium D branded CPUs included "secret" digital rights management features in 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.

Presler

The last generation of Pentium D branded processors was 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. Presler was supported by the same chipsets as Smithfield. It was produced using 65 nm technology similar to Yonah. Presler communicated with the system using an 800 MT/s FSB, and its two cores communicated also using the FSB, just as in Smithfield. Presler also included Intel VT (formerly Vanderpool)–although this was limited to the 9x0 models, and not in the 9x5 models, Intel 64, XD bit, and EIST (Enhanced Intel SpeedStep Technology). Presler was released in the first quarter of 2006 with a 2x2 MB Level 2 cache. Its models included 915, 920, 925, 930, 935, 940, 945, 950, and 960 (with a respective 2.8, 2.8, 3.0, 3,0, 3.2, 3.2, 3.4, 3.4 and 3.6 GHz clock frequency).

All steppings of Presler models 915, 920, 925, 930, and 935, as well as the C1, D0 steppings of 940, 945, and 950 and the 960 D0 stepping were rated at a 95 Watt TDP. All other models (i.e. certain models with 3.2 GHz or faster clock frequencies) were rated at 130 Watt — a 37% increase in power consumption.^[10]

[*] 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.

Smithfield XE

The 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 four logical processors (two physical and two virtual). 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 price) or $1,200 (retail). The only chipsets that worked with the Extreme Edition 840 were 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.

Presler XE

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, had 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 (it could also work with the 955X chipset, though this combination was not supported by Intel). The i975X featured the ICH7R southbridge and supported all LGA 775 (Socket T) Pentium 4, Pentium D, and Pentium Extreme Edition branded processors.

Successor

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

Implementation

In a single-processor scenario, the CPU-to-northbridge 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 bandwidth when under heavy load.

Comparison to Pentium Dual-Core

Intel subsequently released a new line of desktop processors in 2007 based on the Core microarchitecture under the brand Pentium Dual Core. The newer Pentium Dual-Core processors give off considerably less heat (65 W) than the Pentium D (95 W or 130 W). They also only have up to 2 MB L2 Cache memory while the Pentium D has up to 2x2 MB. Despite these differences, the Pentium Dual-Core still outperforms the Pentium D in most applications.

See also

• List of Intel Pentium D microprocessors

References

External links

• Pentium D 800 and 900 Series Review