Gecko's CPU Library

Intel Pentium D (Smithfield) processors

Introduction: May 2005


The Pentium D brand refered 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, but without offering significant upgrades in design, still resulting in a relatively high power consumption. By 2005, the NetBurst processors reached the clock speed barrier at 4GHz due to a thermal (and power) limit exemplified by the Presler's 130W TDP (a high TDP required 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 last shipment date on August 8, 2008 marked the end of the Pentium D brand and also the NetBurst microarchitecture.

The dual-core CPU ran 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 most games, did not benefit from the second core of dual-core CPU over equally clocked single-core CPU. Nevertheless, the dual-core CPU was 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 benefited from the dual-core CPUs.

The Smithfield core

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 3.2GHz 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 3.2GHz 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 2.66GHz with a 533MT/s bus. The relatively cheap 805 was found to be highly overclockable; 3.5GHz was often possible with good air cooling. Running it at over 4GHz 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.

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 1MB of level 2 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-, 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 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. From the P35 onwards, Intel removed support for all NetBurst chips.

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.

Source: Wikipedia, the free encyclopedia.