In computing, the term 3 GB barrier refers to a limitation of some 32-bitoperating systems running on x86microprocessors. It prevents the operating systems from using all of 4 GB (4 × 1024³ bytes) of main memory.^[1] The exact barrier varies by motherboard and I/O device configuration, particularly the size of video RAM; it may be in the range of 2.75 GB to 3.5 GB.^[2]The barrier is not present with a 64-bit processor and 64-bit operating system, or with certain x86 hardware and an operating system such as Linux or certain versions of Windows Server and macOS that allow use of Physical Address Extension (PAE) mode on x86 to access more than 4 GB of RAM.

• Ram For Pentium 4 Motherboard Manual
• Max Ram For Pentium 4

Whatever the actual position of the 'barrier', there is no code in operating system software nor any hardware architectural limit that directly imposes it. Rather, the 'barrier' is the result of interactions between several aspects of both.

In computing, the term 3 GB barrier refers to a limitation of some 32-bit operating systems running on x86 microprocessors.It prevents the operating systems from using all of 4 GB (4 × 1024 3 bytes) of main memory (). May 04, 2011  AFAIK most P4 chipsets support up to 4GB RAM depending on the model of board. Go to www.intel.com and look up the specs on. Online shopping from a great selection at Electronics Store. Dell ATI Radeon Xpress 200 Socket 775 Intel Pentium 4 / Celeron MotherBoard For Optiplex GX320 DT (Desktop) or SMT (Small Mini Tower) Systems Part Numbers: MH651, CU395, UP453, TY915.

Processor/Cache: CPU • Single mPGA478 ZIF Sockets • Supports an Intel® Pentium® 4 processor with 2MB of integrated Advanced Transfer Cache up to 3.4GHz (Extreme Edition). Pentium 4 is a brand by Intel for an entire series of single-core CPUs for desktops, laptops and entry-level servers.The processors were shipped from November 20, 2000, until August 8, 2008.

Physical address limits[edit]

Many 32-bit computers have 32 physical address bits and are thus limited to 4 GB (2³²words) of memory.^[3][4] x86 processors prior to the Pentium Pro have 32 or fewer physical address bits; however, most x86 processors since the Pentium Pro, which was first sold in 1995, have the Physical Address Extension (PAE) mechanism,^[5] which allows addressing up to 64 GB (2³⁶ words) of memory. PAE is a modification of the protected mode address translation scheme which allows virtual or linear addresses to be translated to 36-bit physical addresses, instead of the 32-bit addresses available without PAE.^[6] The CPU pinouts likewise provide 36 bits of physical address lines to the motherboard.^[7]

Many x86 operating systems, including any version of Linux with a PAE kernel and some versions of Windows Server and macOS, can use PAE to address up to 64 GB of memory on an x86 system.^[8][9][10]

There are other factors that may limit this ability to use up to 64 GB of memory, and lead to the '3 GB barrier' under certain circumstances, even on processors that implement PAE. These are described in the following sections.

Chipset and other motherboard issues[edit]

Although, as noted above, most x86 processors from the Pentium Pro onward are able to generate physical addresses up to 64 GB, the rest of the motherboard must participate in allowing RAM above the 4 GB point to be addressed by the CPU. Chipsets and motherboards allowing more than 4 GB of RAM with x86 processors do exist, but in the past, most of those intended for other than the high-end server market could access only 4 GB of RAM.^[11]

This, however, is not sufficient to explain the '3 GB barrier' that appears even when running some x86 versions of Microsoft Windows on platforms that can access more than 4 GB of RAM.

Memory-mapped I/O and disabled RAM[edit]

Modern personal computers are built around a set of standards that depend on, among other things, the characteristics of the original PCI bus. The original PCI bus implemented 32-bit physical addresses and 32-bit-wide data transfers. PCI (and PCI Express and AGP) devices present at least some, if not all, of their host control interfaces via a set of memory-mapped I/O locations (MMIO). The address space in which these MMIO locations appear is the same address space as that used by RAM, and while RAM can exist and be addressable above the 4 GB point, these MMIO locations decoded by I/O devices cannot be. They are limited by PCI bus specifications to addresses of 0xFFFFFFFF (2³² − 1) and below. With 4 GB or more of RAM installed, and with RAM occupying a contiguous range of addresses starting at 0, some of the MMIO locations will overlap with RAM addresses. On machines with large amounts of video memory, MMIO locations have been found to occupy as much as 1.8 GB of the 32-bit address space.^[12]

The BIOS and chipset are responsible for detecting these address conflicts and disabling access to the RAM at those locations.^[13] Due to the way bus address ranges are determined on the PCI bus, this disabling is often at a relatively large granularity, resulting in relatively large amounts of RAM being disabled.^[14]

Address remapping[edit]

x86 chipsets that can address more than 4 GB of RAM typically also allow memory remapping (referred to in some BIOS setup screens as 'memory hole remapping'). In this scheme, the BIOS detects the memory address conflict and in effect relocates the interfering RAM so that it may be addressed by the processor at a new physical address that does not conflict with MMIO.^{[citation needed]} On the Intel side, this feature once was limited to server chipsets; however, newer desktop chipsets like the Intel 955X and 965 and later have it as well.^{[citation needed]} On the AMD side, the AMD K8 and later processors' built-in memory controller had it from the beginning.^{[citation needed]}

As the new physical addresses are above the 4 GB point, addressing this RAM does require that the operating system be able to use physical addresses larger than 2³².^[15] This capability is provided by PAE. Note that there is not necessarily a requirement for the operating system to support more than 4 GB total of RAM, as the total RAM might be only 4 GB; it is just that a portion of it appears to the CPU at addresses in the range from 4 GB and up.^[15]

This form of the 3 GB barrier affects one generation of MacBooks,^[16] lasting 1 year (Core2Duo (Merom) – November 2006 to October 2007): the prior generation was limited to 2 GB, while later generations (November 2007 – October 2009) allowed 4 GB through the use of PAE and memory-hole remapping, and subsequent generations (late 2009 onwards) use 64-bit processors and therefore can address over 4 GB.

Windows version dependencies[edit]

In Microsoft's 'non-server', or 'client', x86 editions of Microsoft Windows (Windows XP, Windows Vista, Windows 7, Windows 8, Windows 8.1, and Windows 10), are able to operate x86 processors in PAE mode, and do so by default as long as the CPU present implements the NX bit.^[17] Nevertheless, these operating systems do not permit addressing of physical memory above the 4 GB address boundary. This is not an architectural limit; it is a limit imposed by Microsoft via license enforcement routines as a workaround for device driver compatibility issues that were (supposedly)^[18] discovered during testing.^[19]

Thus, the '3 GB barrier' under x86 Windows 'client' operating systems can therefore arise in two slightly different scenarios. In both, RAM near the 4 GB point conflicts with memory-mapped I/O space. Either the BIOS simply disables the conflicting RAM; or, the BIOS remaps the conflicting RAM to physical addresses above the 4 GB point,^{[citation needed]} but x86 Windows client editions refuse to use physical addresses higher than that, even though they are running with PAE enabled. The conflicting RAM is therefore unavailable to the operating system whether it is remapped or not.

See also[edit]

• PSE-36 — an alternative to PAE on x86 processors to extend the physical memory addressing capabilities from 32 bits to 36 bits
• RAM disk — a use for remapped RAM
• Virtual memory — which governs the memory available to processes
  • User space — and kernel space, which imposes another limit

References[edit]

1. ^Microsoft Corporation. 'Memory Limits for Windows Releases'. Retrieved 2017-08-07. Devices have to map their memory below 4 GB for compatibility with non-PAE-aware Windows releases. Therefore, if the system has 4GB of RAM, some of it is either disabled or is remapped above 4GB by the BIOS. If the memory is remapped, X64 Windows can use this memory. X86 client versions of Windows don't support physical memory above the 4GB mark, so they can’t access these remapped regions.
2. ^Russinovich, Mark. 'Pushing the Limits of Windows: Physical Memory'. Technet. Microsoft. Retrieved 2017-08-07.
3. ^Matthew Murray (2009-10-27). 'Windows 7: The 64-Bit Question'. PCMag. Retrieved 2017-08-07. A 32-bit system is limited to utilizing 4GB of RAM (2³² addresses)
4. ^Andy Patrizio (2002-07-22). 'AMD Answers the 64-Bit Question'. Wired. Archived from the original on 2008-12-16. Retrieved 2017-08-07. 32-bit processors like Intel's Pentium III/IV and AMD's Athlon have a memory limit of 4 GB per CPU. Any more memory can't be addressed.
5. ^Shanley, Tom (1998). Pentium Pro and Pentium II System Architecture. PC System Architecture Series (Second ed.). Addison-Wesley. p. 445. ISBN0-201-30973-4.
6. ^'Volume 1: Specifications'(PDF). Pentium Pro Family Developer’s Manual. Intel Corporation. January 1996. p. 3–15. Retrieved 2018-12-12. The Pentium Pro processor physical address space is 2³⁶ bytes or 64-Gigabytes (64 Gbyte).
7. ^'Volume 1: Specifications'(PDF). Pentium Pro Family Developer’s Manual. Intel Corporation. January 1996. p. 15-5. Retrieved 2018-12-12. Pin #: C1; Signal Name: A35#
8. ^Microsoft Corporation. 'Memory Limits for Windows Releases'. Retrieved 2017-08-07. Windows Server 2008 Enterprise; Limit in 32-bit Windows: 64 GB
9. ^'Enabling PAE'. Ubuntu Documentation. 2010-05-19. Retrieved 2010-06-07. Physical Address Extension is a technology which allows 32 bit operating systems to use up to 64 GB of memory... PAE is supported on the majority of computers today and it is an easy procedure to enable it in Ubuntu, if it is not already.
10. ^'Linux Kernel'. Fedora Documentation. 2010-05-18. Retrieved 2010-06-07. Fedora 8 includes the following kernel builds: ... The kernel-PAE, for use in 32-bit x86 systems with more than 4GB of RAM, or with CPUs that have an NX (No eXecute) feature.
11. ^Intel Corporation (February 2005). 'Intel Chipset 4 GB System Memory Support'(PDF). Pentium Pro Family Developer’s Manual. p. 7. Archived from the original(pdf) on 2007-03-06. Retrieved 2017-08-07. In uni-processor based systems for mobile, desktop, workstation, and entry level servers, chipsets may be limited to 4 GB of maximum memory. In today’s dual processor Intel server chipsets and workstations, maximum system memory size can be upwards of 16 GB.
12. ^Mark Russinovich (2008-07-21). 'Pushing the Limits of Windows: Physical Memory'. Archived from the original on 2010-06-09. Retrieved 2017-08-07. Windows XP SP2 also enabled Physical Address Extensions (PAE) support by default on hardware that implements no-execute memory because its required for Data Execution Prevention (DEP), but that also enables support for more than 4GB of memory.
13. ^Intel Corporation (February 2005). 'Intel Chipset 4 GB System Memory Support'(PDF). Archived from the original(pdf) on 2007-03-06. Retrieved 2017-08-07. In platforms populated with physical memory sizes approaching 4 GB and greater, onboard system resource requirements will likely not allow the operating system to take advantage of all physical memory populated due to PCI specification requirements and other memory mapped IO resources. Portions of physical memory may overlap with the memory space dedicated to other subsystems and become unavailable to the operating system.
14. ^Intel Corporation (February 2005). 'Intel Chipset 4 GB System Memory Support'(PDF). Pentium Pro Family Developer’s Manual. p. 8. Archived from the original(pdf) on 2007-03-06. Retrieved 2017-08-07.
15. ^ ^abIntel Corporation (February 2005). 'Intel Chipset 4 GB System Memory Support'(PDF). Pentium Pro Family Developer’s Manual. p. 13,14. Archived from the original(pdf) on 2007-03-06. Retrieved 2017-08-07. In order to use remapping, the operating system must be able to address ranges higher than 4 GB of memory.
16. ^'Understanding Intel Mac RAM'.
17. ^Mark Russinovich (2008-07-21). 'Pushing the Limits of Windows: Physical Memory'. Archived from the original on 2010-06-09. Retrieved 2017-08-07. Windows XP SP2 also enabled Physical Address Extensions (PAE) support by default on hardware that implements no-execute memory because its required for Data Execution Prevention (DEP), but that also enables support for more than 4GB of memory.
18. ^Chappell, Geoff. 'Licensed Memory in 32-Bit Windows Vista'. geoffchappell.com. WP:SPS. Retrieved 2014-04-20.
19. ^Mark Russinovich (2008-07-21). 'Pushing the Limits of Windows: Physical Memory'. Archived from the original on 2010-06-09. Retrieved 2017-08-07. The problematic client driver ecosystem led to the decision for client SKUs to ignore physical memory that resides above 4GB, even though they can theoretically address it. […] 4GB is the licensed limit for 32-bit client SKUs.

External links[edit]

Pentium 4^[1][2] is a brand by Intel for an entire series of single-core CPUs for desktops, laptops and entry-level servers. The processors were shipped from November 20, 2000, until August 8, 2008.^[3][4]

All Pentium 4 CPUs are based on the NetBurst architecture. The Pentium 4 Willamette (180 nm) introduced SSE2, while the Prescott (90 nm) introduced SSE3. Later versions introduced Hyper-Threading Technology (HTT).

The first Pentium 4-branded processor to implement 64-bit was the Prescott (90 nm) (February 2004), but this feature was not enabled. Intel subsequently began selling 64-bit Pentium 4s using the 'E0' revision of the Prescotts, being sold on the OEM market as the Pentium 4, model F. The E0 revision also adds eXecute Disable (XD) (Intel's name for the NX bit) to Intel 64. Intel's official launch of Intel 64 (under the name EM64T at that time) in mainstream desktop processors was the N0 stepping Prescott-2M.

Intel also marketed a version of their low-end Celeron processors based on the NetBurst microarchitecture (often referred to as Celeron 4), and a high-end derivative, Xeon, intended for multi-socketservers and workstations. In 2005, the Pentium 4 was complemented by the dual-core-brands Pentium D and Pentium Extreme Edition.

• 2Processor cores
  • 2.2Northwood
  • 2.4Prescott

Microarchitecture[edit]

In benchmark evaluations, the advantages of the NetBurst microarchitecture were unclear. With carefully optimized application code, the first Pentium 4s outperformed Intel's fastest Pentium III (clocked at 1.13 GHz at the time), as expected. But in legacy applications with many branching or x87floating-point instructions, the Pentium 4 would merely match or run slower than its predecessor. Its main downfall was a shared unidirectional bus. The NetBurst microarchitecture consumed more power and emitted more heat than any previous Intel or AMD microarchitectures.

As a result, the Pentium 4's introduction was met with mixed reviews: Developers disliked the Pentium 4, as it posed a new set of code optimization rules. For example, in mathematical applications, AMD's lower-clocked Athlon (the fastest-clocked model was clocked at 1.2 GHz at the time) easily outperformed the Pentium 4, which would only catch up if software was re-compiled 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 their price premium, questionable benefit, and initial restriction to Rambus RAM. In terms of product marketing, the Pentium 4's singular emphasis on clock frequency (above all else) made it a marketer's dream. The result of this was that the NetBurst micro architecture was often referred to as a marchitecture by various computing websites and publications during the life of the Pentium 4. It was also called 'NetBust,' a term popular with reviewers who reflected negatively upon the processor's performance.

The two classical metrics of CPU performance are IPC (instructions per cycle) and clock speed. While IPC is difficult to quantify due to dependence on the benchmark application's instruction mix, clock speed is a simple measurement yielding a single absolute number. Unsophisticated buyers would simply consider the processor with the highest clock speed to be the best product, and the Pentium 4 had the fastest clock speed. Because AMD's processors had slower clock speeds, it countered Intel's marketing advantage with the 'megahertz myth' campaign. AMD product marketing used a 'PR-rating' system, which assigned a merit value based on relative performance to a baseline machine.

At the launch of the Pentium 4, Intel stated that NetBurst-based processors were expected to scale to 10 GHz after several fabrication process generations. However, the clock speed of processors using the NetBurst micro architecture reached a maximum of 3.8 GHz. Intel had not anticipated a rapid upward scaling of transistor power leakage that began to occur as the die reached the 90 nm lithography and smaller. This new power leakage phenomenon, along with the standard thermal output, created cooling and clock scaling problems as clock speeds increased. Reacting to these unexpected obstacles, Intel attempted several core redesigns ('Prescott' most notably) and explored new manufacturing technologies, such as using multiple cores, increasing FSB speeds, increasing the cache size, and using a longer instruction pipeline along with higher clock speeds. These solutions failed, and from 2003 to 2005, Intel shifted development away from NetBurst to focus on the cooler-running Pentium M microarchitecture. On January 5, 2006, Intel launched the Core processors, which put greater emphasis on energy efficiency and performance per clock cycle. The final NetBurst-derived products were released in 2007, with all subsequent product families switching exclusively to the Core microarchitecture.

Processor cores[edit]

Pentium 4 processors have an integrated heat spreader (IHS) that prevents the die from accidentally being damaged when mounting and unmounting cooling solutions. Prior to the IHS, a CPU shim was sometimes used by people worried about damaging the core. Overclockers sometimes removed the IHS from Socket 423 and Socket 478 chips to allow for more direct heat transfer. On processors using the Socket LGA 775 (Socket T) interface, the IHS is directly soldered to the die or dies, making it difficult to remove.

Willamette[edit]

Willamette, the project codename for the first NetBurst microarchitecture implementation, experienced long delays in the completion of its design process. The project was started in 1998, when Intel saw the Pentium II as their permanent line. At that time, the Willamette core was expected to operate at frequencies up to about 1 GHz. However, the Pentium III was released while Willamette was still being finished. Due to the radical differences between the P6 and NetBurst microarchitectures, Intel could not market Willamette as a Pentium III, so it was marketed as the Pentium 4.

On November 20, 2000, Intel released the Willamette-based Pentium 4 clocked at 1.4 and 1.5 GHz. Most industry experts regarded the initial release as a stopgap product, introduced before it was truly ready. According to these experts, the Pentium 4 was released because the competing Thunderbird-based AMD Athlon was outperforming the aging Pentium III, and further improvements to the Pentium III were not yet possible.^{[citation needed]} This Pentium 4 was produced using a 180 nm process and initially used Socket 423 (also called socket W, for 'Willamette'), with later revisions moving to Socket 478 (socket N, for 'Northwood'). These variants were identified by the Intel product codes 80528 and 80531 respectively.

On the test bench, the Willamette was somewhat disappointing to analysts in that not only was it unable to outperform the Athlon and the highest-clocked Pentium IIIs in all testing situations, but it was not superior to the budget segment's AMD Duron.^[5] Although introduced at prices of $644 (1.4 GHz) and $819 (1.5 GHz) for 1000 quantities to OEM PC manufacturers^{[citation needed]} (prices for models for the consumer market varied by retailer), it sold at a modest but respectable rate, handicapped somewhat by the requirement for relatively fast yet expensive Rambus Dynamic RAM (RDRAM). The Pentium III remained Intel's top selling processor line, with the Athlon also selling slightly better than the Pentium 4. While Intel bundled two RDRAM modules with each boxed Pentium 4, it did not facilitate Pentium 4 sales and was not considered a true solution by many.

In January 2001, a still slower 1.3 GHz model was added to the range, but over the next twelve months, Intel gradually started reducing AMD's leadership in performance. In April 2001 a 1.7 GHz Pentium 4 was launched, the first model to provide performance clearly superior to the old Pentium III. July saw 1.6 and 1.8 GHz models and in August 2001, Intel released 1.9 and 2 GHz Pentium 4s. In the same month, they released the 845 chipset that supported much cheaper PC133SDRAM instead of RDRAM.^[6] The fact that SDRAM was so much cheaper caused the Pentium 4's sales to grow considerably.^[6] The new chipset allowed the Pentium 4 to quickly replace the Pentium III, becoming the top-selling mainstream processor on the market.

The Willamette code name is derived from the Willamette Valley region of Oregon, where a large number of Intel's manufacturing facilities are located.^{[citation needed]}

Northwood[edit]

In January 2002, Intel released Pentium 4s with a new core code named 'Northwood' at speeds of 1.6 GHz, 1.8 GHz, 2 GHz and 2.2 GHz.^[7][8]Northwood (product code 80532) combined an increase in the L2 cache size from 256 KB to 512 KB (increasing the transistor count from 42 million to 55 million) with a transition to a new 130 nm fabrication process.^[8] Making the processor out of smaller transistors means that it can run at higher clock speeds and produce less heat. In the same month boards utilizing the 845 chipset were released with enabled support for DDR SDRAM which provided double the bandwidth of PC133 SDRAM, and alleviated the associated high costs of using Rambus RDRAM for maximal performance with Pentium 4.^{[citation needed]}

A 2.4 GHz Pentium 4 was released on April 2, 2002, and the bus speed increased from 400 MT/s to 533 MT/s (133 MHz physical clock) for the 2.26 GHz, 2.4 GHz, and 2.53 GHz models in May, 2.66 GHz and 2.8 GHz models in August, and 3.06 GHz model in November. With Northwood, the Pentium 4 came of age. The battle for performance leadership remained competitive (as AMD introduced faster versions of the Athlon XP) but most observers agreed that the fastest-clocked Northwood-based Pentium 4 was usually ahead of its rival.^{[citation needed]} This was particularly so in mid-2002, when AMD's changeover to its 130 nm production process did not help the initial 'Thoroughbred A' revision Athlon XP CPUs to clock high enough to overcome the advantages of Northwood in the 2.4 to 2.8 GHz range.^[9]

The 3.06 GHz Pentium 4 enabled Hyper-Threading Technology that was first supported in Foster-based Xeons. This began the convention of virtual processors (or virtual cores) under x86 by enabling multiple threads to be run at the same time on the same physical processor. By shuffling two (ideally differing) program instructions to simultaneously execute through a single physical processor core, the goal is to best utilize processor resources that would have otherwise been unused from the traditional approach of having these single instructions wait for each other to execute singularly through the core. This initial 3.06 GHz 533FSB Pentium 4 Hyper-Threading enabled processor was known as Pentium 4 HT and was introduced to mass market by Gateway in November 2002.

On April 14, 2003, Intel officially launched the new Pentium 4 HT processor. This processor used an 800 MT/s FSB (200 MHz physical clock), was clocked at 3 GHz, and had Hyper-Threading technology..^[10] This was meant to help the Pentium 4 better compete with AMD's Opteron line of processors. The server-oriented Opteron initially did not share a common socket with AMD's desktop processor line (Socket A). Because of this, motherboard manufacturers did not initially build motherboards with AGP for Opterons. As AGP was the primary graphics expansion port for desktop use, this oversight prevented the Opteron from encroaching from the server market and threatening the Pentium 4 desktop market. Meanwhile, with the launch of the Athlon XP 3200+ in AMD's desktop line, AMD increased the Athlon XP's FSB speed from 333 MT/s to 400 MT/s, but it was not enough to hold off the new 3 GHz Pentium 4 HT.^[11] The Pentium 4 HT's increase to a 200 MHz quad-pumped bus (200x4=800Mhz effective) greatly helped to satisfy the bandwidth requirements the Netburst architecture desired for reaching optimal performance. While the Athlon XP architecture was less dependent on bandwidth, the bandwidth numbers reached by Intel were well out of range for the Athlon's EV6 bus. Hypothetically, EV6 could have achieved the same bandwidth numbers, but only at speeds unreachable at the time. Intel's higher bandwidth proved useful in benchmarks for streaming operations^{[citation needed]}, and Intel marketing wisely capitalized on this as a tangible improvement over AMD's desktop processors^{[citation needed]}. Northwood 2.4 GHz, 2.6 GHz and 2.8 GHz variants were released on May 21, 2003. A 3.2 GHz variant was launched on June 23, 2003 and the final 3.4 GHz version arrived on February 2, 2004.

Overclocking early stepping Northwood cores yielded a startling phenomenon. While core voltage approaching 1.7 V and above would often allow substantial additional gains in overclocking headroom, the processor would slowly (over several months or even weeks) become more unstable over time with a degradation in maximum stable clock speed before dying and becoming totally unusable. This became known as Sudden Northwood Death Syndrome (SNDS), which was caused by electromigration.^[12]

Pentium 4-M[edit]

Also based on the Northwood core, the Mobile Intel Pentium 4 Processor - M^[13] was released on April 23, 2002 and included Intel's SpeedStep and Deeper Sleep technologies. Intel's naming conventions made it difficult at the time of the processor's release to identify the processor model. There was the Pentium III mobile chip, the Mobile Pentium 4-M, the Mobile Pentium 4, and then just the Pentium M which itself was based on the Pentium III and significantly faster than the former three. Its TDP is about 35 watts in most applications. This lowered power consumption was due to lowered core voltage, and other features mentioned previously.

Unlike the desktop Pentium 4, the Pentium 4-M did not feature an integrated heat spreader (IHS), and it operates at a lower voltage. The lower voltage means lower power consumption, and in turn less heat. However, according to Intel specifications, the Pentium 4-M had a maximum thermal junction temperature rating of 100 degrees C, approximately 40 degrees higher than the desktop Pentium 4.

Mobile Pentium 4[edit]

The Mobile Intel Pentium 4 Processor^[14] was released to address the problem of putting a full desktop Pentium 4 processor into a laptop, which some manufacturers were doing. The Mobile Pentium 4 used a 533 MT/s FSB, following the desktop Pentium 4's evolution. Oddly, increasing the bus speed by 133 MT/s (33 MHz) caused a massive increase in TDPs, as mobile Pentium 4 processors emitted 59.8–70 W of heat, with the Hyper-Threading variants emitting 66.1–88 W. This allowed the mobile Pentium 4 to bridge the gap between the desktop Pentium 4 (up to 115 W TDP), and the Pentium 4-M (up to 35 W TDP).

Gallatin (Extreme Edition)[edit]

In September 2003, at the Intel Developer Forum, the Pentium 4 Extreme Edition (P4EE) was announced, just over a week before the launch of Athlon 64 and Athlon 64 FX. The design was mostly identical to Pentium 4 (to the extent that it would run in the same motherboards), but differed by an added 2 MB of level 3 cache. It shared the same Gallatin core as the Xeon MP, though in a Socket 478 form factor (as opposed to Socket 603 for the Xeon MP) and with an 800 MT/s bus, twice as fast as that of the Xeon MP.

While Intel maintained that the Extreme Edition was aimed at gamers, critics viewed it as an attempt to steal the Athlon 64's launch thunder, nicknaming it the 'Emergency Edition'.^{[citation needed]} With a price tag of $999, it was also referred to as the 'Expensive Edition' or 'Extremely Expensive'.^{[citation needed]}

The added cache generally resulted in a noticeable performance increase in most processor intensive applications. Multimedia encoding and certain games benefited the most, with the Extreme Edition outperforming the Pentium 4, and even the two Athlon 64 variants, although the lower price and more balanced performance of the Athlon 64 (particularly the non-FX version) led to it usually being seen as the better value proposition. Nonetheless, the Extreme Edition did achieve Intel's apparent aim, which was to prevent AMD from being the performance champion with the new Athlon 64, which was winning every single major benchmark over the existing Pentium 4s.

In January 2004 a 3.4 GHz version was released for Socket 478, and in Summer 2004 the CPU was released using the new Socket 775. A slight performance increase was achieved in late 2004 by increasing the bus speed from 800 MT/s to 1066 MT/s, resulting in a 3.46 GHz Pentium 4 Extreme Edition. By most metrics, this was on a per-clock basis the fastest single-core NetBurst processor that was ever produced, even outperforming many of its successor chips (not counting the dual-core Pentium D). Afterwards, the Pentium 4 Extreme Edition was migrated to the Prescott core. The new 3.73 GHz Extreme Edition had the same features as a 6x0-sequence Prescott 2M, but with a 1066 MT/s bus. In practice however, the 3.73 GHz Pentium 4 Extreme Edition almost always proved to be slower than the 3.46 GHz Pentium 4 Extreme Edition, which is most likely due to the lack of an L3 cache and the longer instruction pipeline. The only advantage the 3.73 GHz Pentium 4 Extreme Edition had over the 3.46 GHz Pentium 4 Extreme Edition was the ability to run 64-bit applications since all Gallatin-based Pentium 4 Extreme Edition processors lacked the Intel 64 instruction set.

Although never a particularly good seller, especially since it was released in a time when AMD was asserting near total dominance in the processor performance race, the Pentium 4 Extreme Edition established a new position within Intel's product line, that of an enthusiast oriented chip with the highest-end specifications offered by Intel chips, along with unlocked multipliers to allow for easier overclocking. In this role it has since been succeeded by the Pentium Extreme Edition (The Extreme version of the dual-core Pentium D), the Core 2 Extreme, the Core i7 and most recently, the Core i9.

Prescott[edit]

On February 1, 2004, Intel introduced a new core codenamed 'Prescott'. The core used the 90 nm process for the first time, which one analyst described as 'a major reworking of the Pentium 4's microarchitecture.'^[15] Despite this overhaul, the performance gains were inconsistent. Some programs benefited from Prescott's doubled cache and SSE3 instructions, whereas others were harmed by its longer pipeline. The Prescott's microarchitecture allowed slightly higher clock speeds, but not nearly as high as Intel had anticipated. The fastest mass-produced Prescott-based Pentium 4s were clocked at 3.8 GHz. While Northwood ultimately achieved clock speeds 70% higher than Willamette, Prescott only scaled 12% beyond Northwood. Prescott's inability to achieve greater clock speeds was attributed to the very high power consumption and heat output of the processor. This led to the processor receiving the nickname 'PresHot' on forums.^{[citation needed]} In fact, Prescott's power and heat characteristics were only slightly higher than those of Northwood of the same speed and nearly equal to the Gallatin-based Extreme Editions, but since those processors had already been operating near the limits of what was considered thermally acceptable, this still posed a major issue.^[16]

The 'Prescott' Pentium 4 contains 125 million transistors and has a die area of 112 mm².^[17][18] It was fabricated in a 90 nm process with seven levels of copper interconnect.^[18] The process has features such as strained silicon transistors and Low-K carbon-doped silicon oxide (CDO) dielectric, which is also known as organosilicate glass (OSG).^[18] The Prescott was first fabricated at the D1C development fab and was later moved to F11X production fab.^[18]

Originally, Intel released two Prescott lines: the E-series, with an 800 MT/s FSB and Hyper-Threading support, and the low-end A-series, with a 533 MT/s FSB and Hyper-Threading disabled. Intel eventually added XD Bit (eXecute Disable) and Intel 64 functionality to Prescott.

LGA 775 Prescott uses a rating system, labeling them as the 5xx series (Celeron Ds are the 3xx series, while Pentium Ms are the 7xx series). The LGA 775 version of the E-series uses model numbers 5x0 (520-560), and the LGA 775 version of the A-series uses model numbers 5x5 and 5x9 (505-519). The fastest, the 570J and 571, is clocked at 3.8 GHz. Plans to mass-produce a 4 GHz Pentium 4 were cancelled by Intel in favor of dual core processors, although some European retailers claimed to be selling a Pentium 4 580, clocked at 4 GHz.

The 5x0J series (and its low-end equivalent, the 5x5J and 5x9J series) introduced the XD Bit a.k.a. eXecute Disabled Bit^[19] to Intel's line of processors. This technology, introduced to the x86 line by AMD and called NX (No eXecute), can help prevent certain types of malicious code from exploiting a buffer overflow to get executed. Intel also released a series of Prescott supporting Intel 64, Intel's implementation of the AMD-developed x86-64 64-bit extensions to the x86 architecture. These were originally released as the F-series, and only sold to OEMs, but they were later renamed to the 5x1 series and sold to the general public. Two low-end Intel 64-enabled Prescotts, based on the 5x5/5x9 series, were also released with model numbers 506 and 516. 5x0, 5x0J, and 5x1 series Prescott incorporates Hyper-Threading in order to speed up some processes that use multithreaded software, such as video editing. The 5x1 series also supports 64 bit computing.

Prescott 2M (Extreme Edition)[edit]

Intel, by the first quarter of 2005, released a new Prescott core with 6x0 numbering, codenamed 'Prescott 2M'. Prescott 2M is also sometimes known by the name of its Xeon derivative, 'Irwindale'. It features Intel 64, the XD Bit, EIST (Enhanced Intel SpeedStep Technology), Tm2 (for processors at 3.6 GHz and above), and 2 MB of L2 cache. However, higher cache latency and the double word size, if using Intel 64 mode, negated any advantage that added cache introduced. Rather than being a targeted speed boost the double size cache was intended to provide the same space and hence performance for 64-bit mode operations.

6xx series Prescott 2Ms have incorporated Hyper-Threading in order to speed up some processes that use multithreaded software, such as video editing.

On November 14, 2005, Intel released Prescott 2M processors with VT (Virtualization Technology, codenamed 'Vanderpool') enabled. Intel only released two models of this Prescott 2M category: 662 and 672, running at 3.6 GHz and 3.8 GHz, respectively.^[20][21]

Cedar Mill[edit]

The final revision of the Pentium 4 was Cedar Mill, released on January 5, 2006. This was a die shrink of the Prescott-based 600 series core to 65 nm, with no real feature additions but significantly reduced power consumption. Cedar Mill had a lower heat output than Prescott, with a TDP of 86 W. The Core Stepping of D0 in late 2006 reduced this to 65 watts. It has a 65 nm core and features the same 31-stage pipeline as Prescott, 800 MT/s FSB, Intel 64, Hyper-Threading, but no Virtualization Technology. As with Prescott 2M, Cedar Mill also has a 2 MB L2 cache. It was released as Pentium 6x1 and 6x3 (product code 80552) at frequencies from 3 GHz up to 3.6 GHz. Overclockers managed to exceed 8 GHz with these processors using liquid nitrogen cooling.^[22]

To distinguish Cedar Mill cores from Prescott cores with the same features, Intel added 1 to their model numbers. Thus, Pentium 4 631, 641, 651 and 661 are 65 nm Cedar Mill microprocessors, while Pentium 630, 640, 650 and 660 respectively are their 90 nm Prescott equivalents.

Ram For Pentium 4 Motherboard Manual

The name 'Cedar Mill' refers to Cedar Mill, Oregon, an unincorporated community near Intel's Hillsboro, Oregon facilities.

Successor[edit]

The original successor to the Pentium 4 was (codenamed) Tejas, which was scheduled for an early-mid-2005 release. However, it was cancelled a few months after the release of Prescott due to extremely high TDPs (a 2.8 GHz Tejas emitted 150 W of heat, compared to around 80 W for a Northwood of the same speed, and 100 W for a comparably clocked Prescott) and development on the NetBurst microarchitecture as a whole ceased, with the exception of the dual-core Pentium D and Pentium Extreme Edition and the Cedar Mill-based Pentium 4 HT.

Since May 2005, Intel has released dual-core processors under the Pentium D and Pentium Extreme Edition brands. These came under the code names Smithfield and Presler for the 90 nm and 65 nm parts respectively.

The actual successor to the Pentium 4 brand is the Intel Core 2 brand, released on July 27, 2006. The underlying microarchitecture is the Core microarchitecture, and the first chips implementing it (in 65 nm) are called 'Conroe'. Intel Core 2 processors have been released as single, dual and quad core processors.

Processors implementing the Core microarchitecture were marketed under the 'Core 2'-brand, because processors based on the Yonah-microarchitecture had already been marketed under the Core-brand.

See also[edit]

Notes and references[edit]

1. ^https://pdfs.semanticscholar.org/presentation/cfcc/9d5a7480c4ea87e77084386d74aaff9a1ee1.pdf
2. ^https://web.archive.org/web/20160306140603/http://www.xbitlabs.com/articles/cpu/print/replay.html
3. ^'Intel Introduces The Pentium 4 Processor'. Intel. Archived from the original on 2007-04-03. Retrieved 2007-08-14.
4. ^'Intel intros 3.0 GHz quad-core Xeon, drops Pentiums'. TG Daily. Retrieved 2019-05-17.
5. ^Anand Lal Shimpi (November 20, 2000). 'Intel Pentium 4 1.4GHz & 1.5GHz'. Anandtech.
6. ^ ^abScott Wasson (September 10, 2001). 'The Pentium 4 gets SDRAM: Two new chipsets'. Tech Report.
7. ^Wasson, Scott. AMD's Athlon XP 1800+ processor, Tech Report, October 9, 2001.
8. ^ ^abWasson, Scott and Brown, Andrew. Pentium 4 'Northwood' 2.2 GHz vs. Athlon XP 2000+, January 7, 2002.
9. ^Wasson, Scott. AMD's Athlon XP 2800+ and NVIDIA's nForce2, Tech Report, October 1, 2002.
10. ^Wasson, Scott. Intel's Pentium 4 3.2 GHz processor, Tech Report, June 23, 2003.
11. ^Wasson, Scott. AMD's Athlon XP 3200+ processor, Tech Report, May 13, 2003.
12. ^Shilov, Anton. Sudden Overclocked Northwood Death Syndrome. Is It Strange That Overclocked CPUs Eventually Die?Archived 2007-12-31 at the Wayback Machine, X-bit Labs, December 6, 2002.
13. ^'Mobile Intel Pentium 4 Processor-M Datasheet'. Intel Corp.
14. ^'Intel's Mobile Pentium 4'. Intel Corp.
15. ^'Intel's Pentium 4 Prescott processor'. The Tech Report. February 2, 2004. Retrieved 2007-08-28.
16. ^CPU Heat Comparison: How Hot is Prescott?, AnandTech, 2004-04-16, retrieved 2012-01-08
17. ^Intel Pentium 4 Processor supporting HT Technology 3.40E GHz, ARK.Intel.com, 2004-02-02, retrieved 2012-12-15
18. ^ ^abcdGlaskowsky, Peter N. (2 February 2004). 'Prescott Pushes Pipelining Limits'. Microprocessor Report.
19. ^IT Infrastructure – Intel Resources for IT Managers, Intel.com, retrieved 2012-01-08
20. ^https://ark.intel.com/content/www/us/en/ark/products/27486/intel-pentium-4-processor-662-supporting-ht-technology-2m-cache-3-60-ghz-800-mhz-fsb.html
21. ^https://ark.intel.com/content/www/us/en/ark/products/27488/intel-pentium-4-processor-672-supporting-ht-technology-2m-cache-3-80-ghz-800-mhz-fsb.html
22. ^'OC Team Italy sets a new world record at 8GHz'. NordicHardware. January 22, 2007. Archived from the original on 2008-05-26. Retrieved 2008-01-11.

External links[edit]

• The future of Prescott: when Moore gives you lemons... at Ars Technica

Max Ram For Pentium 4