by Ilya Gavrichenkov
06/24/2007 | 09:32 PM
Almost a year has passed since desktop processors with Core micro-architecture were announced, over this period of time Intel has significantly expanded the line-up of their dual-core Core 2 Duo processors and launched quad-core Core 2 Quad CPUs. However, the maximum clock speed hasn’t really changed. Core 2 Extreme X6800 working at 2.93GHz speed is still the fastest model in the dual-core processor family on Core micro-architecture. Does it mean that Intel gave up the idea of boosting the performance by simply raising the clock frequency and now bets only on additional cores? Not quite.
<%BANNER[article]%>The thing is that frequency increase inevitably leads to increase in processors heat dissipation. And while there is no real competition for Intel in the high-performance segment, they intend to keep the CPU heat dissipation within 65-75W range (for dual-core models). As a result, CPUs with Core micro-architecture can boast not only unprecedented performance, but also a great combination of speed and heat dissipation. And since the “performance per watt” concept is becoming more and more important, it makes Core 2 Duo and Core 2 Extreme processors quite attractive for consumers.
However, we are going to witness a slight increase in the clock speeds of the Core 2 processor family. It will be primarily connected with the faster 1333MHz Quad Pumped Bus that they will support. The corresponding increase of the FSB speed to 333MHz will force Intel to revise the parameters of their solutions: the maximum clock speed in the dual-core and quad-core processor families will now hit 3GHz. Of course, the 2.4% increase in the working frequency of the top processor models is not an impressive achievement at first glance. However, together with higher frequency and bus bandwidth it may eventually result into a serious performance gain.
Today we are going to discuss how big of a performance boost the new processors supporting 1333MHz bus will be able to offer us. Since these processors haven’t been yet officially announced, we will only talk about dual-core Core 2 Duo CPUs this time. We are going to reveal more details on the performance of dual-core and quad-core processors with 1333MHz bus a little later, when they officially launch around mid July 2007.
The processor family supporting 1333MHz bus will consist of four CPUs. They are a quad-core 3GHz Core 2 Extreme QX6850 and three dual-core Core 2 Duo processor models marked as E6850, E6750 and E6550 working at 3.0, 2.66 and 2.33GHz respectively. Until next year this processor family will look exactly like that and then it will be little by little ousted from the market by the new promising Penryn based CPUs.
Shortly before the upcoming launch we managed to get our hands on all three new Core 2 Duo models supporting 1333MHz bus. We summed up their major characteristics in the following table:
Core 2 Duo | Core 2 Duo | Core 2 Duo | |
Processor core | Conroe | ||
Nominal frequency | 3.0 GHz | 2.66 GHz | 2.33 GHz |
Bus frequency | 1333 MHz | ||
Multiplier | 9x | 8x | 7x |
L2 cache | 4 MB | ||
Packaging | LGA775 | ||
Production process | 65 nm | ||
Core stepping | G0 | ||
TDP | 65 W | ||
Vcore | 1.187-1.3525 V | ||
Enhanced Halt State (C1E) Technology | Yes | ||
Enhanced Intel Speedstep | Yes | ||
Execute Disable Bit | Yes | ||
Intel EM64T | Yes | ||
Intel Thermal Monitor 2 | Yes | ||
Intel Virtualization Technology | Yes | ||
As we see, there is nothing really new except higher bus frequency. Our eye catches the new G0 core stepping that will be used for all Core 2 Duo CPUs with 1333MHz bus. This core stepping cannot boast any new technological innovations compared with the traditional B2 core stepping. However, according to Intel, it features slightly better frequency potential and lower power consumption and heat dissipation.
CPU-Z diagnostic utility doesn’t report any innovations in the new CPUs, as well:
Core 2 Duo E6850:
Core 2 Duo E6750:
Core 2 Duo E6550:
There are two things each mainboard needs to support the new processors: FSB 333MHz and G0 core revision support in the BIOS. All mainboards based on Intel chipsets from the “third” series as well as mainboards on Nvidia nForce 600i officially support the new CPUs. Besides, a lot of mainboards for computer enthusiasts built on earlier Intel chipsets can also work with the new processors. You can find the corresponding compatibility data on the mainboard manufacturers’ websites.
Now that the bus frequency has increased, the new processors drop their frequency only down to 2.0GHz when Demand Based Switching (namely, Enhanced Intel SpeedStep and Enhanced Halt State) technologies are active. As a result, when switching to power-saving mode their power consumption and heat dissipation will drop less significantly than in case of CPUs with 1067MHz bus that get their frequency down to 1.6GHz. We performed the corresponding tests and measured the power consumption of similar systems with Core 2 Duo E6750 and Core 2 Duo E6700 processors working at the same frequency of 2.66GHz but supporting different bus frequency.
System power consumption | Core 2 Duo E6750 | Core 2 Duo E6700 |
CPU Burn | 240 W | 250 W |
CPU Idle | 200 W | 202 W |
True, in idle mode with enabled Enhanced SpeedStep technology the system with Core 2 Duo E6700 processors and 1067MHz bus reduces its power consumption more than the same system with Core 2 Duo E6750 CPU. However, as our practical experiments revealed, the new processors are still more economical thanks to the new G0 core stepping.
We decided to compare the performance of the new Core 2 Duo E6850, E6750 and E6550 processors against that of the current top Core 2 Duo CPUs. We have also included the results for AMD Athlon 64 X2 6000+, although it could actually compete only against Core 2 Duo E6600 and Core 2 Duo E6550.
Altogether our test platforms were built with the following hardware components:
We ran the tests with the mainboards BIOS Setup adjusted for maximum performance.
It is evident that quad-core processors will benefit most of all from the transition to 1333MHz bus. They consist of two dual-core halves, each featuring its own L2 cache, and they use front side bus to transfer data between them through system memory. As for the dual-core Core 2 Duo processors, they will improve their performance only thanks to the increased bandwidth of the bus between the processor and the memory. The shift to 1333MHz bus will push the data transfer rate from 8.5 to 10.7GB/s.
In this respect it is extremely interesting to find out how the processor bus frequency affects the performance of Core 2 Duo processors in popular applications. To answer this question we compared the performance of Core 2 Duo E6750 CPU with 1333MHz bus (8 x 333MHz) and Core 2 Duo E6700 CPU with 1067MHz bus (10 x 266MHz). Both processors work at the same clock speed of 2.66GHz.
Core 2 Duo E6750 | Core 2 Duo E6700 | Performance | |
3DMark06 | 10492 | 10364 | 1.2% |
3DMark06, CPU | 2374 | 2298 | 3.3% |
PCMark05 | 8390 | 8325 | 0.8% |
PCMark05, CPU | 6765 | 6521 | 3.7% |
Word 2007, sec | 42 | 43 | 2.4% |
Excel 2007, sec | 43.09 | 43.57 | 1.1% |
7-Zip 4.45, Compressing, | 3847 | 3799 | 1.3% |
AutoGK 2.4/Xvid 1.2, fps | 39.15 | 38.2 | 2.5% |
AutoGK 2.4/DivX 6.6, fps | 57.73 | 57.11 | 1.1% |
H.264 Encoding, | 354 | 359 | 1.4% |
mp3 Encoding, | 123 | 124 | 0.8% |
Photoshop CS3, sec | 82 | 84 | 2.4% |
Sonar 6.2, sec | 119 | 119 | 0.0% |
Premiere Pro 2.0, sec | 190 | 192 | 1.1% |
3ds Max 8 (SPECapc), | 4.02 | 3.96 | 1.5% |
CINEBENCH 9.5 | 835 | 825 | 1.2% |
ScienceMark 2.0, | 1433 | 1433 | 0.0% |
Fritz 9 Chess Benchmark | 3868 | 3784 | 2.2% |
Quake 4, | 122.53 | 116.76 | 4.9% |
Half-Life 2, 1024x768 | 116.42 | 114.92 | 1.3% |
F.E.A.R., Medium Quality | 107 | 105 | 1.9% |
Company of Heroes, | 167.4 | 164.1 | 2.0% |
Supreme Commander | 16428 | 16384 | 0.3% |
Valve Source Engine | 49 | 48 | 2.1% |
The obtained results indicate clearly that the system performance improves just insignificantly from the transfer of the new dual-core processors on Core micro-architecture to faster bus. The performance gain in most cases is only 1%-2%. The maximum performance improvement of 5% occurs in Quake 4, but it is more of an exception, really.
Now that we have found out that higher processor bus bandwidth provides very small performance improvement in systems with dual-core CPUs, the obtained results post no more questions. The already existing and new Core 2 Duo processor families line up strictly according to their clock speed on all diagrams above and further on.
Again no surprises. Core 2 Duo E6850 processor outperforms Core 2 Extreme X6800 by 2-3%. Core 2 Duo E6750 leaves Core 2 Duo E6700 1-2% behind, and Core 2 Duo E6550 is 1-2% slower than Core 2 Duo E6600.
We can see very similar picture in media content encoding tasks. By the way, note the low result of the AMD Athlon 64 X2 6000+ processor that cannot really oppose its competitors in applications of this type.
Maybe systems with DDR3 memory boasting higher bandwidth than DDR2 will ensure better performance improvement with 1333MHz bus. However these systems haven’t yet become widely spread. In the nearest future we are going to devote a series of articles to new processors performance with DDR3 SDRAM that should help us make final conclusions about the advantages of the 25% bus frequency increase.
The situation in rendering applications is quite natural. Processor clock frequency determines the performance results here.
Athlon 64 X2 processors have always been famous for their high results in ScienceMark 2.0 test measuring the systems performance when working with molecular dynamics algorithms. As for Core 2 Duo processors, their results in this test are quite logical and do not need any additional explanations. By the way, I would also like to point out that the model numbering of the dual-core processor solutions proved highly adequate. They reflect the relative Core 2 Duo processors performance very precisely almost all the time.
Nothing unexpected happens here, either. However, I have to stress that Core 2 Duo E6550 processor very often outpaces Core 2 Duo E6600 here. It means that 1333MHz bus appears more important for 3D games than additional 67MHz of clock speed.
Besides a few real games we have also included the results of a benchmark based on Valve Source engine that will be used for future games. It estimates the system performance during the calculation of environmental gaming physics.
We have also included the chess benchmark based on a well-known Fritz 9 engine into this gaming test session.
The results of our performance tests turned out exactly as we have expected them to be and honestly, not very exciting – this is evidently not the main intrigue of the day. It is much more interesting to see how well the new processors will overclock, taking into account that they are built on the new G0 core stepping that is expected to boast better frequency potential. However, on the other hand, the increased to 333MHz FSB frequency may cause new Core 2 Duo to overclock slightly worse than their predecessors. Their frequency multipliers are quite low and hence they are more likely to hit against the unpleasant FSB Wall.
To clear things out, we decided to take a closer look at the frequency potential of the new processors that arrived into our lab. We used the same platform on Asus P5K Deluxe for our overclocking experiments as we used for our performance tests. This mainboard suits perfectly for overclocking CPUs with 1333MHz bus because it maintains excellent stability at high FSB frequencies. Since the clock frequency multipliers of our processors, unlike Core 2 Extreme, cannot be increased beyond their nominal value, we had to overclock by raising the FSB speed. During our overclocking experiments we used Zalman CNPS9700 LED processor cooler. The system stability was checked with SP2004/ORTHOS utility.
The first one to get to the testbed was Core 2 Duo E6850 processor. By raising its Vcore to 1.5V we managed to get it to work at 3.79GHz (9 x 420MHz) without any stability issues.
So, the top model of the three dual-core newcomers allowed a 26% frequency boost without much effort and with the traditional air-cooling involved. It is a pretty good result for the fastest CPU in the family. For instance, Core 2 Extreme X6800 processor we tested earlier (based on B2 core revision) could work stably only at 3.6GHz, not more.
The second overclocking experiment was devoted to Core 2 Duo E6750 with the nominal frequency of 2.66GHz and 8x default clock multiplier. The maximum FSB frequency we managed to achieve for this processor by raising its Vcore to 1.5V was 461MHz.
So, the tested Core 2 Duo E6750 hit 3.69GHz, which is 38% higher than its default spec frequency. This could be a very good achievement if it hadn’t been for one thing. The 461MHz FSB frequency we achieved turned out to be the notorious FSB Wall, because we failed to overcome it with reduced clock frequency multiplier. In other words, the new processors with 1333MHz bus and G0 core stepping are not free from the FSB Wall problem. To our regret.
The third CPU, Core 2 Duo E6550, will definitely be of great interest to overclockers. This is the youngest CPU on G0 core stepping. Its nominal clock frequency is 2.33GHz, it works with 7x multiplier. That is why you can only succeed in overclocking this processor if you have a high-quality mainboard that can push FSB to 500MHz and up. Asus P5K Deluxe that we used is one of these boards. We managed to overclock our processor to the maximum of 3.57GHz with the Vcore increased to 1.5V.
To hit this frequency we raised the FSB to 510MHz thus getting a 53% frequency increase above the nominal. Note that in this case we didn’t hit the FSB Wall but simply exhausted the processor capabilities.
So, new Core 2 Duo processors with 1333MHz bus overclock pretty well. The new G0 core stepping obviously proved up to the mark here.
Well, let’s sum up a few things now. Intel’s decision to equip their Core 2 Duo processors with faster 1333MHz bus support is regarded as another move towards higher performance of this processor family. It is partially true. As we have seen today, higher bus speed will obviously boost the performance in most applications. However, unfortunately, this boost will not be as significant as we hoped: it hardly ever gets beyond 3%. But, the changes in the bus frequency are not the only thing that determined the advantage of the new CPUs over their predecessors: different clock frequencies are another reason. For example, the nominal frequency of the top Core 2 Duo E6850 model has now risen to 3.0GHz, while before today the maximum frequency of the existing Core 2 Duo processors used to be only 2.93GHz. This also affects the performance, and together with the faster bus it brings in more confident victory of the top Core 2 Duo CPUs. In other words, the launch of the Core 2 Duo CPUs with 1333MHz bus will become another part of the progress CPUs on Core micro-architecture are making. Although we all wish that they were moving at a little bit faster pace towards the promising Penryn family.
Higher bus frequency is not the only nice thing about the new processors. They are based on the new G0 stepping of the Conroe core that boasts better frequency potential. As a result, the FSB Wall has been pushed farther back and the overclocking results have improved significantly. For example, our overclocking experiments revealed that the new processors can work at 3.6-3.8GHz with traditional air-cooling onboard. Therefore, Core 2 Duo E6850, 6750 and 6550 should become very popular among overclockers, especially since Intel is going to price them very affordably. According to the preliminary data, Core 2 Duo E6850 will sell for $266, Core 2 Duo E6750 - for $183, and Core 2 Duo E6550 – for $163. This attractive price tag will certainly help Intel stimulate the transition to systems with 1333MHz bus.