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Core 2 Duo notebook processor (CPU)

The Intel Core 2 Duo (also known as Core2 Duo) notebook processor is a 64 bit dual core processor. This means two processor cores work inside a Core 2 Duo in parallel.

The Core 2 Duo, which was introduced on July 27 2006, is the direct successor of the Core Duo. Each core is based on the Pentium M micro architecture. Compared with the old Netburst architecture of the Pentium 4, the cores in the Core 2 Duo have shorter pipelines. As a result, the maximum clock rate is lower but the performance per clock is significantly higher. Thus a Pentium 4M with the same clock rate is up to 40% slower.

Both, the notebook Core 2 Duo and the desktop Core 2 Duo are based on the same processor. However, the notebook version runs with a lower voltage (0.95 to 1.188 volt) and a lower front side bus (1066 vs. 667 MHz). As a result (and because of slower laptop hard discs) the performance of notebooks is about 20% lower than their desktop counterparts with the same clock rate.

Key Features

  • 64 bit support
  • Dual core processor with shared level 2 cache
  • Execute Disable Bit
  • Partially Intel Virtualization Technology (VT)
  • Socket M (starting from Santa Rosa socket P)
  • 291 million transistors

Performance

The performance of the Core 2 Duo processor in comparison with its direct competitor, the AMD Turion 64 X2, is very good. The Core 2 Duo beats the AMD Turion 64 X2 with the same clock rate in virtually all applications (on average by 15%). The energy consumption is similar in both processors. In comparison with the predecessor Core Duo, the Core 2 Duo is about 10% faster and consumes a bit more energy (More details further below).

Specifications

The Core 2 Duo processors are produced in 65 nm (and later in 45nm), contain 14 stages pipelines and 2-4 MB level 2 cache (depending on the model). The features of the Core 2 Duo are:

x86 architecture
The Intel Core 2 Duo uses the x86  instruction set, which was introduced in 1978 with the 8086/8088 processor. Furthermore it supports the multimedia extension MMX, SSE2, SSE3 and SSE4.

Dual core technology
Two processor cores run with the same frequency in the same processor building block and share the level 2 cache as well as the front side bus (FSB).

Execute Disable Bit
Prevents security problems through buffer overflows, if the operation system supports it and if it is activated.

Wide Dynamic Execution *
Every core can execute four complete commands simultaneously. 

Smart-Memory-Access *
Shorter idle times, improved data transfer and faster out-of-order command execution lead to better usage of the pipeline and as a result to higher performance.

Advanced-Smart-Cache *
Like the Core Duo, the Core 2 Duo has shared level 2 cache and each core receives the same amount of cache. Intel doubled the bandwidth to the level 1 cache though.

Advanced-Digital-Media-Boost *
One 128-Bit SSE command is now output per clock cycle.

Virtualisation technology (VT)
The Intel VT offers hardware support for virtual systems on one computer (use of several isolated operation systems at the same time e.g. through Xen or VMWare).
Beware, not all models support VT (especially the cheaper ones dont).

64 bit support *
Support of 64 bit wide words in the CPU. This means the processor can handle 64 bit data packets. The Intel Core 2 Duo supports the AMD64 extension (licensed), through which 32 and 64 bit programs can run on the CPU (if a 64 bit operation system is used).

Theoretically, a 64 bit processor can access more than 4 GB of  memory, but this is usually limited by the chip set used.

 

* This feature was newly introduced with the Core 2 Duo.

Energy saving functions

Like with the previous version, the clock rate and voltage can be set dynamically and individually for each core (Speedstep). Under light load the processor can save energy by lowering the clock speed (to 1200 MHz respectively 800 MHz with the Santa Rosa) and the core voltage (from 1.3 Volt to 1.0375 Volt). This happens with virtually no performance losses, thanks to the automatic adjustment of the clock speed. Additionally, the processor can turn off parts of the CPU which are not used, to save energy.

Intel Dynamic Power Coordination
Coordinates the Enhanced Intel SpeedStep technology and the Idle Power-Management State (C-state) transitions independent of the core.

Enhanced Intel Deeper Sleep with Dynamic Cache Sizing
Writes data from the cache to the main memory during inactivity. As a result, the CPU voltage can be lowered which saves energy.

Intel Dynamic Bus Parking
Allows the chip set to shut down during inactivity to save energy.

Advanced Power Gating
Parts of the CPU core can be shut down through "Advanced Power Gating". This can even happen if performance is required, to improve the performance per watt ratio.

Enhanced Deep C4 Sleep State
The core voltage can be further reduced, if the level 2 cache is turned off.

Split Bus Array
Buses and arrays are separated in order to set them individually into energy saving mode during certain operation states.

Santa Rosa update

Dynamic FSB Switching
Dynamic FSB Switching
Dynamic Acceleration
Dynamic Acceleration
Longer Deeper Sleep
Longer Deeper Sleep

On Mai 9th 2007 the Core 2 Duo processor was upgraded for the 4th Centrino generation called Santa Rosa. The processor is still based on the Merom core, but some energy saving functions and optimisations were added. Furthermore, it now needs the socket P with 478 pins, which isn't compatible with the socket M of the older Core 2 Duo.

In contrast with  its predecessor, the new Core 2 Duo processors now run with a 800 MHz FSB (200 MHz quad-pumped) instead of 667 MHz (133 MHz quad-pumped).

The FSB now supports "Dynamic front side bus switching", whereas the FSB can be lowered from 200 MHz to 100 MHz under light processor load, to save energy. This drop only affects the chipset and CPU and is thus called "virtual". With speedstep, the Core 2 Duo can slow down to a minimum of 1.2 GHz. Thanks to the lower (virtual) FSB, the "Santa Rosa" Core 2 Duo can drop even more, to 800 MHz, to save even more energy.

 

Another new feature is the dynamically overclocking of the core, called "Dynamic Acceleration". If only one core is used, it can be dynamically overclocked, while the second core stays in the energy saving C3-modus. Therefore the overclocked core can work with the clock speed of the next higher model (e.g. 2.2 instead of 2.0 GHz with the T7300), without any change in the TDP (thermal design power) and without the need for more cooling.

If idle, the processor will start one of the various saving modes (C1 to C4/DC4). The chipset of the Santa Rosa keeps the processor as long as possible in energy saving mode (e.g. by preventing memory acces).

 

Penryn Update

In Jannuary 2008 Intel introduced the new T9xxx and T8xxx Core 2 Duo processors of the new "Penryn" core. These CPUs are produced in 45nm (instead of the 65nm before) and offer a bigger Level 2 Cache (3 and 6 MB versus 2 and 4 before). Furthermore, the Penryn core has a faster division engine and 47 new SSE instructions (SSE4). Due to the 45 nm process, Intel was able to increase the core speed without increasing the current consumption.

Compared to a similar clocked Merom Core 2 Duo, the Penryn is on average between 5-10% faster. The speed increase is mostly because of the bigger L2 Cache. Detailled benchmarks of the new Penryn CPUs can be found in our Intel Core 2 Duo Penryn review.

Downward compatibility

The Core 2 Duo prior to the introduction of Santa Rosa is, like its predecessor, still based on the PGA socket-M interface. It is thus possible, to upgrade some notebooks from Core Duo to Core 2 Duo. However, a Bios which supports the Core 2 Duo is necessary and the processor must not be soldered to the Mainboard (which is the case with the BGA - ball grid array - case).

Following chipsets theoretically support a Core 2 Duo:

Intel 945GM: Core 2 Duo, LV, ULV
Intel 945GMS: Core 2 Duo LV und ULV
Intel 945PM: Core 2 Duo, LV, ULV
Intel 940GML: Doesen't support the Core 2 Duo

Core Duo versus Core 2 Duo

The Core 2 Duo (Merom) architecture shows several advantages compared with the Core Duo (Yonah). Especially the 64 bit extension allows now the use of 64 bit operation systems and thus 4 GB memory (limited by the chipset). Furthermore, the Merom got a bigger level 2 cache and the architecture was widened:

  • An additional "Simple Decoder"
  • Maximum Decode Rate 4+1 compared with 3 of the Yonah core
  • 96 to 80 entries in the reorder buffer
  • +1 issue ports (6 versus 5)
  • 32 scheduler entries (versus 24)
  • Seperated FP Units
  • 3 SSE Units (Yonah 1)
  • An additional integer ALU

Furthermore, the pipeline was extended from 12 to 14. This allows a higher clock rate but means the speed per clock is lower (this is compensated by the afore mentioned widening of the architecture). [Source]

The benchmarks in our performance comparison between Core Duo T2400 and Core 2 Duo T5600 showed results ranging from -0.3% to 34% (on average about 10%). The energy consumption rose significantly however, which might be caused by the early Bios. > read the report

Models

Intel Core 2 Duo Box

The energy consumption of the processors is shown in the letter in front of the type number:

X ... Extreme (fastest) version with the highest energy consumption, see next paragraph
E ... >=55 watt (desktop)
T ... 30-39 watt (standard version in notebooks)
P ... max 25 watt
L ... 12-19 watt (low voltage)
U ... <11.9 watt (ultra low voltage)

The following 4-digit number shows built (first number) and performance (the other three numbers). The Core 2 mobile processors are supposed to get 5XXX and 7XXX (currently T2XXX for Core Duo and T1XXX for Core Solo).

The Core 2 Duo was introduced on July 31st 2006 (the FSB 800 version with DAT - Dynamic Acceleration Technology on May 9th 2007). Apart from that, starting from the middle of 2007 the topversion is called Core 2 Extreme X.

A detailed list of all current models is here: Mobile processor overview.

A list of all mobile processors according to performance is here: Benchmarklist of mobile prozessors.

 

Show Restrictions
PosModelCodenameL2 Cache + L3 CacheTDP WattTDP TurboMHz - TurboCores / ThreadsCinebench R15 CPU Single 64BitCinebench R15 CPU Multi 64BitCinebench R23 Single CoreCinebench R23 Multi Corex265Blender v3.3 Classroom CPU(-)7-Zip Single7-ZipGeekbench 5.5 Multi-CoreGeekbench 6.4 Single-CoreGeekbench 6.4 Multi-CoreWebXPRT 4 OverallCrossMark Overall
Intel Core 2 Duo T9900Penryn6MB3530602/2
Intel Core 2 Duo T9800Penryn6MB3529202/2
Intel Core 2 Duo P9700Penryn6MB2828002/2
Intel Core 2 Duo T9600Penryn6MB3528002/2
Intel Core 2 Duo (Desktop) E6850Conroe4MB6530002/2
Intel Core 2 Duo P9600Penryn6MB2526602/2
Intel Core 2 Duo T9550Penryn6MB3526602/2
Intel Core 2 Duo T9500Penryn6MB3526002/2
Intel Core 2 Duo (Desktop) E6700Conroe4MB6526602/2
Intel Core 2 Duo SP9600Penryn6MB2525302/2
Intel Core 2 Duo P9500Penryn6MB2525302/2
Intel Core 2 Duo T9400Penryn6MB3525302/2
Intel Core 2 Duo P8800Penryn3MB2526602/2
Intel Core 2 Duo T9300Penryn6MB3525002/2
Intel Core 2 Duo T7800Merom4MB3526002/2
Intel Core 2 Duo P8700Penryn3MB2525302/2
Intel Core 2 Duo SP9400Penryn6MB2524002/2
Intel Core 2 Duo (Desktop) E6600Conroe4MB6524002/2
62
117
Intel Core 2 Duo P8600Penryn3MB2524002/2
65
118
PosModelCodenameL2 Cache + L3 CacheTDP WattTDP TurboMHz - TurboCores / ThreadsCinebench R15 CPU Single 64BitCinebench R15 CPU Multi 64BitCinebench R23 Single CoreCinebench R23 Multi Corex265Blender v3.3 Classroom CPU(-)7-Zip Single7-ZipGeekbench 5.5 Multi-CoreGeekbench 6.4 Single-CoreGeekbench 6.4 Multi-CoreWebXPRT 4 OverallCrossMark Overall
Intel Core 2 Duo T8300Penryn3MB3524002/2
Intel Core 2 Duo T7700Merom4MB3424002/2
Intel Core 2 Duo SP9300Penryn6MB2522602/2
Intel Core 2 Duo P8400Penryn3MB2522602/2
Intel Core 2 Duo P7570Penryn3MB2522602/2
Intel Core 2 Duo P7550Penryn3MB2522602/2
Intel Core 2 Duo T7600Merom4MB3423302/2
Intel Core 2 Duo T6770Penryn2MB3523002/2
Intel Core 2 Duo T7500Merom4MB3522002/2
Intel Core 2 Duo SL9600Penryn6MB1721302/2
Intel Core 2 Duo P7450Penryn3MB2521302/2
Intel Core 2 Duo T7400Merom4MB3421602/2
Intel Core 2 Duo T6670Penryn2MB3522002/2
Intel Core 2 Duo T6600Penryn2MB3522002/2
Intel Core 2 Duo T8100Penryn3MB3521002/2
Intel Core 2 Duo T5900Merom2MB3522002/2
Intel Core 2 Duo P7370Penryn3MB2520002/2
Intel Core 2 Duo P7350Penryn3MB2520002/2
Intel Core 2 Duo T7300Merom4MB3420002/2
Intel Core 2 Duo T6570Penryn2MB3521002/2
PosModelCodenameL2 Cache + L3 CacheTDP WattTDP TurboMHz - TurboCores / ThreadsCinebench R15 CPU Single 64BitCinebench R15 CPU Multi 64BitCinebench R23 Single CoreCinebench R23 Multi Corex265Blender v3.3 Classroom CPU(-)7-Zip Single7-ZipGeekbench 5.5 Multi-CoreGeekbench 6.4 Single-CoreGeekbench 6.4 Multi-CoreWebXPRT 4 OverallCrossMark Overall
Intel Core 2 Duo T6500Penryn2MB3521002/2
Intel Core 2 Duo T5850Merom2MB3421002/2
Intel Core 2 Duo SL9400Penryn6MB1718602/2
Intel Core 2 Duo SL9380Penryn6MB1718002/2
Intel Core 2 Duo T6400Penryn2MB3520002/2
Intel Core 2 Duo T5870Merom2MB3420002/2
Intel Core 2 Duo T7200Merom4MB3420002/2
Intel Core 2 Duo T5800Merom2MB3520002/2
Intel Core 2 Duo T7250Merom2MB3520002/2
Intel Core 2 Duo T5750Merom2MB3420002/2
Intel Core 2 Duo L7700Merom4MB1718002/2
Intel Core 2 Duo SP7700Merom4MB2018002/2
Intel Core 2 Duo T7100Merom2MB3418002/2
Intel Core 2 Duo T5670Merom-2M2MB3518002/2
Intel Core 2 Duo SL9300Penryn6MB1716002/2
Intel Core 2 Duo T5600Merom2MB3418302/2
Intel Core 2 Duo T5550Merom2MB3418302/2
Intel Core 2 Duo T5500Merom2MB3416602/2
Intel Core 2 Duo T5470Merom-20482MB3516002/2
Intel Core 2 Duo T5450Merom-20482MB3416602/2
PosModelCodenameL2 Cache + L3 CacheTDP WattTDP TurboMHz - TurboCores / ThreadsCinebench R15 CPU Single 64BitCinebench R15 CPU Multi 64BitCinebench R23 Single CoreCinebench R23 Multi Corex265Blender v3.3 Classroom CPU(-)7-Zip Single7-ZipGeekbench 5.5 Multi-CoreGeekbench 6.4 Single-CoreGeekbench 6.4 Multi-CoreWebXPRT 4 OverallCrossMark Overall
Intel Core 2 Duo T5300Merom2MB3417302/2
Intel Core 2 Duo SP7500Merom4MB2016002/2
Intel Core 2 Duo SU9600Penryn3MB1016002/2
Intel Core 2 Duo T5200Merom2MB3416602/2
Intel Core 2 Duo L7500Merom4MB1716002/2
Intel Core 2 Duo T5270Merom-20482MB3514002/2
Intel Core 2 Duo T5250Merom-20482MB3415002/2
Intel Core 2 Duo L7300Merom4MB1714002/2
Intel Core 2 Duo SU9400Penryn3MB1014002/2
Intel Core 2 Duo SU7300Penryn3MB1013002/2
38.7n2
72.2n2
208
392
0.46
1450n2
2514.5n2
392
Intel Core 2 Duo SU9300Penryn3MB1012002/2
Intel Core 2 Duo U7700Merom-20482MB1013302/2
Intel Core 2 Duo L7100Merom4MB1712002/2
Intel Core 2 Duo U7600Merom-20482MB1012002/2
Intel Core 2 Duo U7500Merom-20482MB1010602/2
(-) * Smaller values are better. / n123 Number of benchmarks for this median value / * Approximate position
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Klaus Hinum, 2007-12-21 (Update: 2012-05-26)