Intel Core 2
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Core 2 is an eighth-generation x86 architecture microprocessor produced by Intel and based on the Intel Core microarchitecture; successor of the NetBurst microarchitecture that has powered most Intel processors since 2000. Core 2 also marks the retirement of Intel's Pentium brand name that has been used from 1993 and the reunion of Intel's notebook and desktop product lines since Pentium M was released apart from Pentium 4 in 2003.
The first wave of Core 2 processors was officially released on July 27, 2006. Like the Intel Core brand that it supersedes, Core 2 offers Duo (dual-core) and Solo (single-core) models. New product lines include the Extreme (high-end) model and the Quad (quad-core) model. The base processors are codenamed "Conroe" (Desktop) and "Merom" (Portable); their variants have codenames such as "Kentsfield" (quad-core Conroe) and "Penryn" (45nm Merom). Although the "Woodcrest" server CPUs are also based on Core microarchitecture, they are marketed under the Xeon brand rather than Core 2. As of December 2006, all Core 2 Duo processors are fabricated on 300mm wafers in Fab 12 in Arizona and Fab 24-2 in Ireland. The 65nm manufacturing process was developed at Intel's Oregon D1D facility.
Unlike NetBurst-based processors, such as the Pentium 4 and Pentium D, Core 2 does not stress designs based on extremely high clock speeds but rather improvements in the processors usage of both available clock cycles and power. This translates into more efficient decoding stages, execution units, caches, and buses, as well as many other factors. The cpu-family may also have more than one core on a single chip. The power consumption of these processors is much lower than the Pentium desktop line of products. With a TDP of only 65 W, Core 2 features a significantly reduced power consumption compared to its predecessor desktop chip, the Pentium 4 Prescott with a TDP of 130 W.
Intel Core 2 processors feature EM64T, Virtualization Technology, Execute Disable Bit, and SSE3. Core 2 also introduced LaGrande Technology, Enhanced SpeedStep Technology, and Active Management Technology (iAMT2).
Current processor cores
The first Intel Core 2 Duo processor cores, codenamed Conroe and given the Intel product code 80557, were launched on July 27, 2006 at Fragapalooza. These processors are built on a 65 nm process and are intended for desktops, replacing the Pentium 4 and Pentium D. Intel has claimed that Conroe provides 40% more performance at 40% less power compared to the Pentium D. All Conroe processors have 4 MB L2 cache; however, the E6300 and E6400 versions have half of their cache disabled, hence they only have 2 MB of usable L2 cache.
The lower end E6300 (1.86 GHz) and E6400 (2.13 GHz), both with a 1066 MT/s FSB, were released on July 27, 2006. Traditionally, CPUs of the same family with less cache simply have the unavailable cache disabled, since this allows parts that fail quality control to be sold at a lower rating. At launch time, Intel's prices for the Core 2 Duo E6300 and E6400 processors were $183 USD and $224 USD each in quantities of 1000. Conroe CPUs have an enormous value with their overclocking capabilities — the 1.86 GHz model has been shown to overclock to over 3.0 GHz with a good motherboard supporting high FSB speeds. In these reports, an overclocked Core 2 Duo 1.86 GHz was shown to eclipse the Core 2 Extreme in certain benchmarks. According to well respected reviews, the E6300 and E6400 only suffers on average 3.5% because of the smaller L2 cache size. With the higher overclock of the two processors, enthusiasts can easily make up the 3.5% percent by overclocking further than its higher end Conroe cousins. However, the low multiplier on these two lower-end chips requires a very high FSB to reach high speeds, which few motherboards support.
The higher end Conroe processors are labeled as the E6600 and E6700 Core 2 Duo models, with the E6600 clocked at 2.4 GHz and the E6700 clocked at 2.67 GHz. The family has a 1066 MT/s front side bus, 4 MB shared L2 cache, and 65 watts TDP. These processors have been tested against AMD's current top performing processors (Athlon 64 FX Series), which were, until this latest Intel release, the fastest CPUs available, and the vanilla Conroe boasts much faster performance. Overclocking results show that the E6700 and E6600 are stable when overclocked to 4 GHz with air cooling and to 5.4 GHz with liquid nitrogen cooling, despite having locked multipliers.
At launch time, Intel's prices for the Core 2 Duo E6600 and E6700 processors were $316 USD and $530 USD each in quantities of 1000.
The top-of-the-line Core 2 Extreme was officially released on July 29, 2006. However some retailers appear to have released it on July 13, 2006, albeit at a high premium. The less powerful E6x00 models of Core 2 Duo were scheduled for simultaneous release with the X6800, which are both available at this time. It is powered by the Conroe XE core and replaces the Pentium 4 Extreme Edition and the dual-core Pentium Extreme Edition processors. Core 2 Extreme has a clock speed of 2.93 GHz and a 1066 MT/s FSB, although it was initially expected to achieve 3.33 GHz and 1333 MT/s. The TDP for this family is 75-80 watts. At full load the X6800 does not exceed 45 °C (113 °F), and with SpeedStep enabled the average temperature of the CPU when idle is essentially that of the ambient atmosphere. 
At launch time, Intel's price for the Core 2 Extreme X6800 was $999 USD each in quantities of 1000. Like the desktop Core 2 Duo, it has 4 MB of shared L2 cache available. This means that the only major difference between the regular Core 2 Duo and Core 2 Extreme is the clock speed, which is unusual for the "Extreme Edition." It does come with an unlocked multiplier, however, allowing it to basically simulate any E6x00 with 4 MB of L2 cache. This also allows it to gain a better overclocking ability than the other Core 2 processors, with up to a 11X multiplier. Intel's previous Extreme Editions all included a unique feature, such as an increased FSB, more L2 cache, or addition of L3 cache.
Overclocking proves more promising, as Intel allows the user to change the multiplier number. The X6800 has shown the ability to be overclocked to 3.6 GHz on Intel's stock cooler with no increase in voltage to the system components, 4.1 GHz with good air cooling and increased voltage, and 5.7 GHz with liquid nitrogen cooling.
For a very long time, it was considered that stripped down versions of the Conroe processors were code-named Allendale. In actuality, Allendale is a code-name for a different processor. Many suggest that E6300 and E6400 are actually code-named Allendale, however, the E6300 (1.86 GHz) and E6400 (2.13 GHz) processors are not code-named Allendale because they physically have 4 MB cache, same as their big brothers E6600 and E6700 - it is just that half of their physical memory is disabled. Traditionally, CPUs of the same family with less cache simply have the unavailable cache disabled (this allows parts that fail quality control to be sold at a lower rating). The fact that E6300 and E6400 are not code-named Allendale and actually code-named Conroe has been confirmed by Intel themselves.
Quoted from The Tech Report:
You'll find plenty of sources that will tell you the code name for these 2 MB Core 2 Duo processors is "Allendale," but Intel says otherwise. These CPUs are still code-named "Conroe," which makes sense since they're the same physical chips with half of their L2 cache disabled. Intel may well be cooking up a chip code-named Allendale with 2 MB of L2 cache natively, but this is not that chip.
The real Allendale processors, including the E4300, will be released during Q1 2007. The real Allendale processors use a smaller mask with only 2 MB of cache, thereby increasing the number of chips per platter. Allendale processors are LGA775, 65nm chips which have 800MT/s (200MHz * 4) FSB rather than Conroe's 1066MT/s FSB (266MHz * 4).
Merom, the first mobile version of the Core 2, was officially released on July 27, 2006 but quietly began shipping to PC manufacturers in mid-July alongside Conroe. Merom is Intel's premier line of mobile processors, with largely the same features as Conroe but with more emphasis on low power consumption to enhance notebook battery life. Intel has claimed that Merom will provide 20% more performance yet maintain the same battery life as the Yonah-based Core Duo. Merom will be the first Intel mobile processor to feature EM64T 64-bit extensions.
Intel has stated that the first version of Merom is drop-in compatible with the current Core Duo platform, requiring at most a BIOS update. It has the same thermal envelope and the same 667 MT/s bus rate.
The Merom processors are labeled as the "T5x00" and "T7x00" Core 2 Duo models, with the T5200 clocked at 1.60 GHz, the T5500 clocked at 1.66 GHz, the T5600 clocked at 1.83 GHz, the T7200 clocked at 2.0 GHz, the T7400 clocked at 2.16 GHz, and the T7600 clocked at 2.33 GHz. The T5x00 models come with 2 MB of shared L2 cache, and the T7x00 models come with 4 MB of shared L2 cache. Both have the Intel product code 80537.
Kentsfield is the codename for the first quad-core version of the Core 2 processor. The first model of Kentsfield, the Core 2 Extreme QX6700 (product code 80562), was released on November 2, 2006, and became available from manufacturers such as Dell and Gateway on November 14. The processor features four cores, with a clock speed of 2.67 GHz, and two 4 MB L2 caches. The new processor retails for a price of $999, the same as the Core 2 Extreme X6800.
Initial samples of the processor had substantially higher power consumption than their Core 2 Duo counterparts (approx. 130 watts), however the retail version is expected to have a thermal envelope of 80 W. The top-of-the-line Kentsfield CPU, the first and only Kentsfield to be released thus far, is branded a Core 2 Extreme processor, while the forthcoming mainstream versions will be called Core 2 Quad. Unlike AMD's 4x4 (which refers to two dual-core processors on one motherboard), Kentsfield is a one socket solution; for example, the QX6700 is actually two E6700 chips connected together by a 1066 MT/s FSB on one MCM, resulting in lower costs but less bandwidth to the northbridge. What this also means is that it will be easy for Core 2 Duo early adopters to upgrade their LGA775 platform by just dropping in a quad-core Kentsfield, as has been demonstrated by AnandTech when they dropped in two Core 2 Quad processors in place of two WoodCrests in a Mac Pro.
As can be expected, four cores scale very well in multi-threaded applications, such as video editing, ray-tracing, or rendering, where the performance doubles compared to an equally clocked Core 2 Duo. However single or dual-threaded applications, for example most games, will not benefit from the additional cores. For single threaded applications, initial performance reports indicate that this relatively small increase in FSB and processor speed does not dramatically increase overall performance alone; however, it does leave more room for high-speed, low latency RAM to significantly boost the numbers. Nevertheless, multitasking several processor-demanding single threads will see a dramatic overall performance boost; gamers may yet want to look at Kentsfield for the potential to run several instances of their favorite game or games without noticeable performance lag in each, as each instance (up to four) could be running on a different processor.
In October 2006, leaked Intel roadmaps unveiled that Intel plans to release four additional Core 2 Duo Processors. The release in 2007 will coincide with that of the Intel Bearlake chipset. The new processors will be the Core 2 Duo E6650, E6750, E6800, and E6850. Processors with a number ending in "50" will have a 1333 MT/s FSB. The processors will all have 4 MB of L2 cache. Their clock frequency will be similar to that of the already released processors with the same first two digits (E6600, E6700, X6800).
As noted above, Intel plans to release mainstream versions of the Kentsfield quad-core processor, and brand them Core 2 Quad. (mainstream version is Q6600,Q6400)
The successor to the Merom, code-named Penryn will most likely debut the 45 nanometer process that will be also used for the Kentsfield sequel, Yorkfield. Announcements about Penryn are expected by mid-2007. Its successor should be Nehalem.
Earlier media reports suggested Yorkfield to be an octa-core (eight-core) processor consisting of 2 dies with four cores each. However the newest rumours indicate that Yorkfield will be the quad-core successor to the Kentsfield processor. It will have a 45 nanometer process, and be a single die design, unlike the Kentsfield, which has been compared to basically two separate Conroe cores in one socket. The Yorkfield will have 8 MB of fully shared L2 cache (the Kentsfield has two separate 4MB L2 caches, shared separately by each pair of processors). An across-the-board increase in bus speed (connection to the northbridge, etc.) to be greater than 1333 MT/s is hoped for by this point, as all processors will be primarily limited by the bus bandwidth. This may prove to be difficult, as past advancements in bus speed have come coupled with changes in how the data is sent. Yorkfield is also expected to be released supporting DDR3 memory (1333 MHz DDR), as suggested by certain enthusiast websites.
An E4300 Allendale (1.8 GHz, 800 MT/s FSB) will be released in the 1st quarter of 2007.
Merom was released on July 27, 2006, and has since been adopted by notebook manufacturers.
A second wave of Merom processors featuring an 800 MT/s FSB and using the new Socket P is expected to launch in April 2007.  These chips will be part of the platform codenamed Santa Rosa. Low voltage versions are also planned for release in the same timeframe.
Intel will offer a low-cost single-core version of Conroe, code-named "Conroe-L", starting from the second quarter 2007, according to an article on DailyTech. The new Conroe-L processors will not carry the Core nomenclature. Instead Intel is resuscitating the Pentium and Celeron brands for Conroe-L based products.
The New Conroe-L processors shall be named Pentium E2xxx series. It supports 800MHz FSB and only has 1MB L2 Cache.
Conroe, Conroe XE and Allendale all use Socket LGA775; however, not every motherboard is compatible with these processors. Supporting chipsets are:
- Intel: 865PE, 945P/PL/G, 955X, 975X, P/G/Q965, Q963, 946GZ/PL;
- ATi: ATI's Radeon Xpress 200, RD600 and RS600
- nVidia: nForce 4 SLI Intel Edition, nForce 570/590 Intel Edition and nForce 680i/650i.
- VIA: PT880/PT880 Ultra, PT890, PM880 and PM890.
- SiS: SiS662
- See also: List of Intel chipsets
Although a motherboard may have the required chipset to support Conroe, many motherboards based on the above mentioned chipsets do not support Conroe. This is because all Conroe-based processors require a newer voltage regulator module (VRM), named VRM 11. This requirement is a result of Conroe's significantly lower power consumption, compared to the Pentium 4/D CPUs it is replacing. A motherboard that has both a supporting chipset and VRM 11 supports Conroe processors, but even then some boards will need an updated BIOS to recognize Conroe's FID (Family ID) and VID (Voltage ID).
DDR2 Memory Modules
Unlike the previous Pentium 4 and Pentium D design, the Core 2 technology sees a greater benefit from memory running synchronously with the Front Side Bus (FSB). This means that for the Conroe CPUs with FSB of 1066 MT/s, the ideal memory speed is PC2-4200. In some configurations, using PC2-5300 can actually decrease performance. Only when going to PC2-6400 is there a significant performance increase. While expensive DDR2 memory models with tighter timings do improve performance, the difference in real world games and applications is negligible.
The Core 2 processor does not require the use of DDR2. While the Intel 975X and P965 chipsets require this memory, some motherboards and chipsets support both the Core 2 and DDR memory. When using DDR memory, performance may be reduced because of the lower available memory bandwidth.
The pricing for various models of Core 2, in lots of 1000 to OEMs, at the time the processors were released, can be found in the list of Intel Core 2 microprocessors. It should be noted that these prices are what it costs system builders such as Dell and HP to stock Core 2 processors. There are no set MSRPs for Core 2 CPUs in the retail channel - prices at retailers are usually very close to the above mentioned prices, but are dependent on what the supplier is charging to stock these CPUs as well as supply and demand.
A set of abbreviations has, over time, come into common use for Intel Pentium processors. Standard abbreviations include P1 (Pentium), P2 (Pentium II), P3 (Pentium III),P3-M (Pentium III-Mobile), P4, PM, P4-M, and so on, though it does conflict with the codenames P5, 'P6', and so on.
With the release of the new Core 2 processor, the abbreviation C2 is often used, as well variants C2D (the present Core 2 Duo), and C2Q, C2E to refer to the Core 2 Quad and Core 2 Extreme processors respectively.
- List of Intel Core 2 microprocessors
- Intel Core
- ^ Collection of reviews with benchmarks. Retrieved on 2006-07-17.
- ^ Shimpi, Anand Lal. Intel's Core 2 Extreme & Core 2 Duo: The Empire Strikes Back. AnandTech. Retrieved on 2006-07-28.
- ^ Schmid, Patrick; Töpelt, Bert. Game Over? Core 2 Duo Knocks Out Athlon 64. Tom's Guide Publishing. Retrieved on 2006-07-17.
- ^ http://www.nordichardware.com/news,4970.html
- ^ Cool and Cheap Screamers from Intel and AMD. The Tech Report (2006-08-08). Retrieved on 2006-11-22.
- ^ Intel's Core 2 Duo chips arrive early. MacNN. Retrieved on 2006-07-21.
- ^ Intel second quarter 2006 earnings release; see page 3 (PDF). Intel (2006-07-19). Retrieved on 2006-07-21.
- ^ Spring IDF 2006: Merom and Ultra Mobile PCs. AnandTech. Retrieved on 2006-07-17.
- ^ Intel's Core 2 Extreme QX6700: The Multi-core Era Begins. AnandTech. Retrieved on 2006-11-11.
- ^ Intel Core 2 Extreme QX6700. Bit-Tech. Retrieved on 2006-11-11.
- ^ "Kentsfield" to Debut at 2.66 GHz. DailyTech. Retrieved on 2006-09-29.
- ^ The Quad Squad. CNET. Retrieved on 2006-11-12.
- ^ Intel "Kentsfield" Named Core 2 Quad. DailyTech. Retrieved on 2006-09-29.
- ^ Intel Kentsfield Preview. X-bit labs. Retrieved on 2006-09-29.
- ^ "Conroe" Refresh Details Unveiled. DailyTech. Retrieved on 2006-10-17.
- ^ Second-Generation Quad-Core Chip from Intel to Come in Q3 2007.. X-bit labs. Retrieved on 2006-10-01.
- ^ Olsen, Sven. Intel Forecasts "Santa Rosa" for April 2007.. DailyTech. Retrieved on 2006-07-17.
- ^ Kubicki, Kristopher. Intel 2006 Mobile CPU Roadmap Update. DailyTech. Retrieved on 2006-07-17.
- ^ Olsen, Sven. "Conroe-L": Core 2 Duo on the Cheap. Daily Tech. Retrieved on 2006-08-12.
- ^ Huynh, Anh. Intel "Conroe-L" Details Unveiled. Daily Tech. Retrieved on 2006-09-23.
- ^ Intel Core 2: Is high speed memory worth its price?. Madshrimps. Retrieved on 2006-08-01.
- Intel® Centrino® Duo Mobile Technology papers
News reports on the Core 2 product launch:
- Intel Core Microarchitecture
- Intel's press release announcing Core 2
- Intel's Core 2 page
- Announcing Intel Core 2 Duo
- The second coming of Intel's Core Duo
Selection of Core 2 Reviews (see the full list of 50 reviews here):
- Intel Core 2 Extreme QX6700 Quad Core - Launch Review
- Intel Core 2 Extreme QX6700 - Product Review
- Intel Core 2 Extreme QX6700 Quad Core
- Core 2 Extreme (Kentsfield) Quad Core CPU Review
- Intel's Core 2 Duo processors
- Core 2 Duo & Core 2 Extreme
- Contemporary Dual-Core Desktop Processors Shootout
- Core 2 Duo & Extreme Processors Performance Analysis
- Intel Core 2 Performance, Overclocking, Power Usage
- Intel Core 2 Gaming Performance
- Intel's Core 2 Duo and Core 2 Extreme processors
- Intel's Core 2 Extreme & Core 2 Duo: The Empire Strikes Back
- Intel Conroe Core 2 Duo/Extreme Processors
- Game Over? Core 2 Duo Knocks Out Athlon 64
- Intel Core 2 Duo - Test
- Intel Core 2 Duo- Which Offers the Best Bang for the Buck?
- Intel's Core 2 Quadro Kentsfield: Four Cores on a Rampage