Core 2 Duo processors: shock and tremor

Author: Vladimir Romanchenko, Andrey Kuzin, Dmitriy Sofronov

Introduction

In fact, we can't talk solely about the processor debut of the Conroe core, because by tradition Intel has presented a comprehensive solution – new processors combined with the new family of Intel 965 chipsets which will be the basis for various platform solutions like gaming PCs, entertainment systems, office computers, etc.

Nevertheless, our today's material is devoted solely to the practical aspect of research into the real capabilities of the new-generation processors – to start with, those in combination with the flagship "desktop" Intel 975X chipset. In fact, with this review we are opening a course of research works devoted to the capabilities of Core 2 Duo processors in various environments - in combination with various motherboards based on various chipsets, video cards, and other components.

As the very first tests of new processors have shown, there is indeed much to investigate. Even the heading of today's article chosen not for the sake of a witticism: at long last, the manufacturer of processors has gladdened us with not the traditional 10-20% but a two-fold performance boost combined with a real reduction in the chip temperature.

We hope the readers will forgive us the so emotional introduction especially when they see the results of tests. Anyway, before we move on to the lab let me give you a more detailed account of the specifications of today's tests. At least, to understand then how such impressive results come out at the benchmarks.

For the first time, the details of the Core 2 Duo architecture was announced at IDF Spring 2006. It's just when we came to know the new improvements of the Core architecture. In fact, the names of the new processor brands by Intel for desktop PCs - Core 2 Duo and Core 2 Extreme - became known some time later, in May 2006. Once exhaustive information on chips with the working name Conroe has appeared, it makes sense to publish a consolidated theoretical material on the new generation of the Core micro architecture. Those who for some reasons have missed the article Evolution of the multi-core Intel Core processor architecture: Conroe, Kentsfield.., or already forgot its main theses, should refresh the information, which will help us easier to comprehend the test results.

Today, we'd better mention the key specifications of Core 2 Duo and Core 2 Extreme inherited from Intel Pentium M and enriched with the best developments of the NetBurst architecture and a number of brand-new technologies:

• The Intel Wide Dynamic Execution - a technology that allows executing greater number of instructions executed per cycle, thus improving the efficiency of running applications and reducing the power consumption. Each core of the processor is now able executing up to four instructions simultaneously using the 14-stage pipeline
• The Intel Intelligent Power Capability - a technology that enables specific components of the chip only when needed, which gives a substantial reduction in the power consumption on the whole.
• The Intel Advanced Smart Cache - a technology of using the common L2 cache memory by all the cores, which gives an overall reduction in the power consumption, and at the same time one of the processor cores may use up the whole cache memory once the other core is disabled dynamically
• The Intel Smart Memory Access - a technology for the memory subsystem optimization that reduces the response time and increases the bandwidth of the memory subsystem
• The Intel Advanced Digital Media Boost - a technology that allows processing 128-bit SSE, SSE2, and SSE3 commands widely used in multimedia and graphic applications in one cycle

Additionally to these, the core uses the most recent 65-nm process technology introduced for the manufacture of new dual-core chips, which has given an additional saving in the power consumption and allows raising the boundary clock speed of the chips (of course, as compared to the "next of kin" which offer a similar micro architecture – Intel Core Duo family processors). The speeds of Core 2 Duo amount to 800 or 1066 MHz, the L1 cache for each core is 32 K for data and instructions, respectively; the capacity of the total distributed L2 cache is 2 MB or 4 MB.

Finally, what is left is to sort out with the specific questions. The pinout of the new processors is clear - it is the well-know LGA775. On the other hand, the marking of the processors has undergone essential changes. We can't say the combination of the letter prefix with a 4-digit index that follows it is so unexpected, especially that the mobile Core and Core Duo processors have been marked this way for at least half a year. Anyway, such designation is new for the desktop platforms.

This is what stands behind the new 5-character marking of Intel processors for desktop and mobile systems. The letter index at the beginning of the marking classified the TDP of the processor, without any relation to the form factor:

• X - TDP over 75W
• E - TDP of 50W and higher
• T - TDP within 25W to 49W
• L - TDP within 15W to 24W
• U - TDP of about 14W and less

In its turn, the 4-digit index also has a meaning. In the general case, the higher the 4-digit number in the CPU marking is, the higher performance and power consumption it offers. At the same time, the first digit means the belonging of the chip to a certain product family, and the second one stands for the respective ranking within the family. Therefore, the greater the figure is, the higher is the performance of the chip.

Here are a few examples of how the marking of modern processors looks and what stands behind the notation:

• Core 2 Extreme X6800 – 2.93 GHz, 4 MB L2 cache, 1066 MHz FSB
• Core 2 Duo E6600 – 2.4 GHz, 4 MB L2 cache, 1066 MHz FSB
• Core 2 Duo E6400 – 2.13 GHz, 2 MB L2 cache, 1066 MHz FSB
• Core Duo T2500 – 2 GHz, 2 MB L2 cache, 667 MHz FSB
• Core Duo U2500 – 1.06 GHz, 2 MB L2 cache, 533 MHz FSB

Needless to say, such method of chip marking has no connection to the PR ratings of AMD processors which pretend for some relative correspondence to some MHz of a reference CPU; all is much simpler: the greater the figure is, the higher is the performance of the chip. Perhaps, after the infamous finish of the discredited system of performance rating that takes only the clock speed into account, this is the only method of real-time "rough" estimation of overall properties of the chip, without going deep into the detailed specifications. As regards the new method of marking Intel chips that has come as a replacement to the formerly used 3-digit combination, we finally can breathe with relief: now the graphics and the processors by all the main players of the market offer a similar structure of names - now all depends on who will be the first to to move to 5-digit numbers. ;-)

This is about all with the introduction, and we now move on to describing the test setup and the tests.

The testing procedure

It looks tempting, of course - to merge all the currently topical processor types and compare their real capabilities. However, for today we decided to confine to the most characteristic chips made by Intel – because the top-end processor by AMD is still a thing that you can come across for our editorial board, and we are against running tests of platform an in offhanded way.

On the other hand, comparison of five LGA775 Intel chips for various sectors - from the very low-end up to the very top is an effective way to estimate the scales of the changes and imagine the future price positioning of the previous generation processors once the novelties have hit the retail.

Here are participants of the tests:

• Intel Core 2 Extreme X6800 – Conroe, Dual Core, 65 nm, 2.93 GHz (multiplier x11, unlocked), 4 MB L2 cache, 1066 MHz FSB, TDP 75W; support for Enchanced Intel SpeedStep, Intel Virtual Technology, Intel EM64T, Execute Disable Bit, operation with only 975X and P965 chipsets (Q965 and S965 are not supported);
• Intel Core 2 Duo E6700 - Conroe, Dual Core, 65 nm, 2.66 GHz, 4 MB L2 cache, 1066 MHz FSB, TDP 65W;
• Intel Pentium 4 Extreme Edition 3.73 GHz – Prescott2M, HT, 90 nm, 3.73 GHz, 2 MB L2 cache, 1066 MHz FSB, TDP 115W;
• Intel Pentium 4 670 3.8 GHz - Prescott, 90 nm, HT, 3.8 GHz, 2 MB L2 cache, 800 MHz FSB, TDP 115W;
• Intel Pentium 4 D820 - SmithField, Dual Core, 90 nm, 2.8 GHz, 2 x 1 MB L2 cache, 800 MHz FSB, TDP 89W;
• Intel Pentium 4 520 - Prescott, 90 nm, HT, 2.8 GHz, 1 MB L2 cache, 800 MHz FSB, TDP 84 W;
• Intel Celeron D 331 - Prescott, 90 nm, 2.66 MHz, 256K L2 cache, 800 MHz FSB (4 õ 200 MHz).

Let's take a closer look at the "new kids".

This is how the engineering sample of the most powerful chip, Intel Core 2 Extreme X6800, looks.

This is the information displayed by the CPU-Z utility.

This is the sample of Core 2 Duo E6700 (2.66 GHz).

Information about Intel Core 2 Duo E6700 displayed by CPU-Z.

Don't be confused by the mysterious label SSE4 among the specifications of the processors - it is just the way the set of capabilities added to the new version of the Core micro architecture is recognized.

We ran the tests on a system with the following components:

• Motherboard Intel D975XBX, ATX form factor, Intel 975X Express chipset with the most recent BIOS version (Rev. 1209);
• Memory – 2 x 512 MB Corsair XMS2 667 MHz;
• Graphic subsystem NVIDIA GeForce 7950GX2 1 GB (ForceWare 91.31);
• Graphic subsystem ATI X1900 XTX CrossFire Edition 512 MB (Catalyst 6.5);
• Cooling system - ThermalTake Big Typhoon;
• PSU - HIPER HPU-4R580-MU;
• Operating system – Windows XP (5.1.2600), SP2, DX9.0c.

On the screenshots with the BIOS settings, you can see that the motherboard successfully recognized the CPU Intel Core 2 Extreme X6800. The BIOS settings allow varying many settings within wide ranges.

We should note a few interesting points which we came across while operating the absolutely new components. First of all – it is the unusual 8-pin connector for additional power supply of the Intel D975XBX motherboard, which has appeared instead of the customary 4-pin connector. Alas - our search for a PSU with the respective connector in the Moscow retail failed. So we had to "emulate" this connector in a rough-and-ready fashion, after which all went on wheels.

Another important point is the heat emission of the processors. However intensive the load was, and however demanding the benchmark was, the heat emission of both these new processors was consistently low. Especially astounding thing was the found upon the replacement of processors, when the reverse side of the motherboard left slightly warm and not hot as usual.

Moreover, during one of the experiments the cooler ThermalTake Big Typhoon left unfastened and was simply lying on top of the Core 2 Duo E6700 at that moment fully loaded and ran not "noticing" such a "prank". Of course, new generations of processors are always expected to provide a more or less significant performance boost, but it is perhaps the first time that we have seen such an impressive superiority over the predecessors at the reduction in heat emission.

It is now high time we estimated the performance of the novelties. Now on to the benchmarking.

System benchmarks

Both the new processors showed impressive results while running PCMark05, however the most impressive "spikes" that finally affected the overall PCMark Score were seen in the CPU and Memory tests. Especially impressive were the peaks of performance boost while handling 4 K and 192 K portions, which shows an effective organization of the cache operation.

Tests run with SiSoft Sandra 2005 show simply a hurricane performance boost. While formerly the results were compared on the base of clock speeds alone, now can't regard the results for Intel Core 2 Duo E6700 and Core 2 Duo E6700 as other than tricks of "extraterrestrial" technology – even the dual-core SmithField was left well behind.

It should be noted that, as a continuation of this topic, in the forthcoming material we intend to give a special emphasis to the research of operation of new chips while running applications optimized for multithreading – e.g. MP3-encoding, 3D rendering, archiving etc., as well as simultaneous execution of several similar tasks. However, in our first material in Core 2 Duo chips we decided to give a maximum emphasis to the most spectacular 3D tests. There is indeed something worth looking at.

3D benchmarks

While the old tests like AquaMark 3 or 3DMark03 can't thrill anybody any longer with tens of thousands "marks", the substantial superiority of the new architecture at the results of the most recent 3DMark05 and especially 3DMark06 simply invalidate all what was formerly achieved.

We try hard to restrain our emotions, but we can't put it in a different way: Intel simply knocked out its old NetBurst architecture. It is even a nightmare to imagine how Athlon 64 will rank versus Core 2 Duo processors …

Well, next comes a cruel but needed Coup de Grâce. Gaming tests.

A complete unconditional surrender. The white flag and entreaty for mercy cried by the party biting the dust are neither seen not heard because of the noise of tossed up hats and applause to the winner.

Final Words

We see a complete victory of the Conroe core and the Core micro architecture. The consolidated complex of new technologies – increase in the number of commands executed per cycle up to four; efficient power consumption, rearrangement of the cache memory operation, distributed L2 cache; optimization of the memory subsystem operation, handling 128-bit commands per cycle and much more - have brought Intel to the cherished goal, sharp rise in the key indicators of modern processors - performance per cycle, and performance per watt.

For so long we have not seen a new processor architecture that is able showing a multiple superiority in performance! In view of the fact that any new processor architecture within half a year after the announcement is building up its capabilities, it is even fearful to imagine the potential surprises the Core 2 Duo series is bringing to us. We should note that the retail will see forthcoming Core 2 Duo chips of even more power-saving stepping that that presented in our tests.

What's next? How regrettable it is to inform, but it's high time the chips built on the Intel NetBurst architecture retired, and the niche of inexpensive low-end processors has to be cleared for the Core 2 Duo so that they could earlier reach at least the mainstream sector. As regards the rivals from the AMD camp, we need to run a series of tests to make declare the final verdict. Anyway, the intuition prompts you that the new Core 2 Duo are too tough for them.

And that seems to be that way for a long time.