PENTIUM D

The 'Pentium D'^[2] brand refers to two series of dual-core 64-bit x86 processors with NetBurst microarchitecture. The CPUs comprised of two single-core dies in one package (called a Multi-Chip Module). The 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 exeplified by the ''Presler's'' 130 W TDP (a high TDP requires an 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] marked 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 video editing, ray-tracing, rendering, and compressing). 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 ''application''s 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 ''application''s rarely run alone on computers under Microsoft Windows, Linux, BSD-family, operating systems. In such multitasking environments, when an antivirus software is running in the background of another program, or where several CPU-intensive ''application''s are running simultaneously, each core of the ''Pentium D'' branded processor can handle different program, improving the overall performance over its single-core ''Pentium 4'' counterpart.

Contents

Smithfield

Presler

Pentium Extreme Edition

Smithfield

Presler

Successor

Implementation

See also

References

External links

Smithfield

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 ''CPU''s 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 ''CPU''s 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.

Presler

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 ''CPU''s. 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 at here

Pentium Extreme Edition

Smithfield

Original Pentium Extreme Edition logo.

Pentium Extreme Edition logo as of 2006.

'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.

Presler

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 only run 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.

Successor

Main articles: 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.

Implementation

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. 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.

See also

★ List of Intel Pentium D microprocessors

References

1. Product Change Notification, 107779 - 00
2. The Pentium D: Intel's Dual Core Silver Bullet Previewed
3. The 65 nm Pentium D 900's Coming Out Party: Test Setup
4. The 65 nm Pentium D 900's Coming Out Party: The 65 nm NetBurst
5. The 65 nm Pentium D 900's Coming Out Party: Thermal Design Power Overview
6. Intel Moves From Dual Core To Double Core: 65 nm Intel Double Core Preslers Forward
7. Intel intros 3.0 GHz quad-core Xeon, drops Pentiums
8. A 4.1 GHz Dual Core at 0 - Can it be True?
9. The 65 nm Pentium D 900's Coming Out Party: Thermal Design Power Overview

External links

★ Intel Pentium D Official Website

★ Pentium D 800 and 900 Series Review

★ Intel Pentium D technical specifications