Intel Core 2 Extreme QX6850: Four Cores at Three Gigahertz

To hit new performance heights the quad-core Intel processor for computer enthusiasts uses 1333MHz bus and operates at 3.0GHz speed. However, what is really interesting about it, is the new G0 processor stepping lowering the heat dissipation and improving the chip’s overclocking potential.

by Ilya Gavrichenkov
07/15/2007 | 09:00 PM

The first desktop processors based on Core micro-architecture were launched almost a year ago. These CPUs that came to replace the NetBurst based solutions represented new Intel’s concept. This concept declared the end of “gigahertz chase” and put absolutely new processor features atop of the priority list. The primary focus was then on the most optimal balance between the performance and power consumption. That is why the direct comparison between the top Core 2 Duo processors announced in 2006 and the today’s latest models may be pretty discouraging. The maximum clock frequency of CPUs on Core micro-architecture hasn’t really increased over the past year. Over this period of time Intel has launched a few new CPU models with lower clock speeds and smaller L2 cache memory that were targeted for low-cost computer systems, however, they haven’t got into production of CPUs with frequencies beyond 2.93GHz. This is how the new concept has actually kicked in: further frequency increase would cause CPU power consumption to get higher and it will not be comparable with the performance improvement resulting from it, thus making processor like that power-inefficient.


However, it is impossible to claim that no progress has been made in terms of Core based processor improvement. Without touching the maximum clock speed, Intel engineers managed to double the number of computational cores in their solutions. Now top processors with Core micro-architecture feature four cores instead of two. And their clock frequency is not any lower than that of the dual-core models. This particular change ensured that top models in the lineup received a significant performance boost.

So, by the first birthday of Intel’s Core micro-architecture the company could already boast some real success stories, such as significant CPU performance boost as well as considerable strengthening of their position in the market. However, Intel marketing people felt they needed more than that. Therefore, today the company is launching a few new dual-core and quad-core models that would push up the maximum frequency of the Core 2 processor family: today the top processors on Core micro-architecture will conquer 3GHz milestone.

On the one hand, we cannot really claim that the launch of 3.0GHz processor is a significant step forward, because it actually means that the operating frequency has got only 67MHz higher. However, on the other hand, these new processor can boast one more advantage compared with the predecessors: they support faster 1333MHz system bus with 10.7GB/s peak bandwidth. The 25% increase in processor bus frequency should be a more important factor that would help raise the performance of Intel solutions to a new level.

Besides the launch of 3GHz processor on two and four cores, Intel is also officially announcing a few dual-core processors with lower working frequencies and the same 1333MHz bus support. The table below contains the full list of new solutions coming out today together with their major specifications and pricing:

We have already introduced to you the first processors with 1333MHz bus in our article called New Member In Core 2 Duo Processor Family: Introducing CPUs with 1333MHz Bus. So, today we are going to discuss the new top solution from Intel designed for computer enthusiasts – the quad-core Core 2 Extreme QX6850.

Core 2 Extreme QX6850: Closer Look

Although Intel paid special attention to launching their new Core 2 Extreme QX6850 processor, there aren’t that many technological innovations in it. In fact, it is a quad-core processor we all know as Kentsfield featuring faster 1333MHz bus and working at higher 3GHz clock frequency. So, let’s move on to its formal specifications right away:

Core 2 Extreme QX6850

Processor core


Nominal frequency

3.0 GHz

Bus frequency

1333 MHz



L2 cache

2 x 4 MB

Number of cores




Manufacturing process

65 nm




130 W


1.100V-1.372 V

Enhanced Halt State (C1E) Technology


Enhanced Intel Speedstep


Execute Disable Bit


Intel EM64T


Intel Thermal Monitor 2


Intel Virtualization Technology


As you can see from the table above, Core 2 Extreme QX6850 has no new electrical or thermal characteristics to offer us compared with its quad-core predecessors. The traditional report from CPU-Z diagnostic tool also proves it.

Nevertheless, this processor is based on the new G0 stepping and I would like to draw your attention to this particular fact. The thing is that this processor stepping will eventually be used in all quad-core Intel processors thus pushing the maximum temperatures up and typical heat dissipation of some selected models down. This way, Core 2 Quad processors with G0 stepping are not only expected to become cooler and more economical, but also should be able to boast better overclocking potential.

For the mainboard to be compatible with the new Core 2 Extreme QX6850 processor it needs two things: 333MHz FSB support and BIOS modification to support G0 processor stepping. The boards built around Intel’s “third series” core logic and those on Nvidia nForce 600i chipsets are formally compliant with these requirements. However, there are a few other mainboards for computer enthusiasts based on different chipset solutions that support the new Intel processors. You can retrieve more compatibility details on the corresponding manufacturers’ web-sites.

Processor Family on Core Micro-Architecture

The launch of CPUs with 1333MHz bus to the market, put the final touch onto shaping up the processor family on Core micro-architecture. The next big change in the Intel desktop segment is planned for next year, when new Penryn solutions with 45nm cores are scheduled to come out. So, we decided to sum up all the dual-core and quad-core processors on Core micro-architecture in a single table that should make it easier to perceive all the processor ratings and models names within different price categories.

(For details on Intel Trusted Execution Technology go here.)

Although processors with Core micro-architecture appeared in the market pretty recently, Intel managed to discontinue some of them by this time. In particular, the launch of quad-core Core 2 Extreme QX6800 and QX6850 processors put an end to the life cycle of the dual-core Core 2 Extreme X6800 CPU. Moreover, the release of dual-core Core 2 Duo CPUs with 1333MHz bus will very soon eliminate all Core 2 Duo E6000 models with 1066MHz bus support.

Testbed and Methods

It is evident that Core 2 Extreme QX6850 has no direct competitors at this time. We have already seen that quad-core Kentsfield processors can deliver the highest performance during our AMD Quad FX platform tests. Quad-core Intel processors outperform the alternative dual-socket AMD solution, and the same working frequencies as those of dual-core processors on Core micro-architecture make them superior to all Intel’s solutions. Therefore, our today’s test session is more of a nominal nature.

Nevertheless, in order to estimate the advantage the new three-gigahertz quad-core CPU from Intel can provide, we compared its performance against that of other contemporary dual-core and quad-core CPUs, including Quad FX platform. Moreover, to ensure we get an objective look at the overall picture, we have also included the results of the dual-core Intel processors with 1333MHz bus. Thanks to the increased variety of testing participants we managed to put together all performance data for the CPUs above $160.

Our test platforms were built using the following hardware components:

We ran the tests with the mainboards BIOS Setup adjusted for maximum performance.


Futuremark, Synthetic Benchmarks

Popular 3DMark06 and PCMark06 benchmarks create multi-threaded workload, so quad-core processors perform bets of all here. The advantage of Core 2 Extreme QX6850 with 1333MHz bus over the Core 2 Extreme QX6800 in these tests lies between 0.6% and 3.8%.

Office Applications

Microsoft Word 2007 is a typical office application, however quad-core Kentsfield processors are slightly faster than dual-core Conroe CPUs working at the same clock speed and supporting the same bus frequency. It is obviously explained by the larger L2 cache memory of the quad-core processors.

As for Microsoft Excel and 7-zip, Core 2 Extreme QX6850’s triumph is indisputable here. Moreover, these office applications seem to be extremely sensitive to growing processor bus frequency. Core 2 Extreme QX6850 is 3.5% faster than Core 2 Extreme QX6800 in both applications, which is more than their relative frequency difference of only 2.3%.

Audio and Video Encoding

We see pretty similar results during video encoding tests. All contemporary codecs can really take advantage of multi-core processor features. They also get a boost from faster bus between the processor and memory subsystem. As a result, Core 2 Extreme QX6850 is a leader during video encoding tests.

As for the audio encoding with Apple iTunes, the situation here is a little different. The thing is that this codec can only create two threads at the same time, which doesn’t make the use of quad-core CPUs as efficient as it could be. However, despite this fact, Kentsfield processors can still ensure a performance boost over Conroe thanks to larger L2 cache.

Image, Audio and Video Editing

Professional applications for creation and processing of multimedia content have been long optimized for multi-processor systems. Therefore, multi-core CPUs perform at a very high level in tasks of this type. This advantage is extremely significant in Adobe Premiere pro and Cakewalk Sonar. As for Adobe Photoshop, not all of its filters are optimized for multi-core CPUs, so the performance difference between dual-core and quad-core processors here is lower.

Final Rendering

The results of the final rendering tests are quite logical. The number of processor cores had the primary effect on the results in this test, while the CPU clock speed appears secondary. In other words, the performance difference between Core 2 Extreme QX6850 and Core 2 Extreme QX6800 is pretty similar to their frequencies delta.

Scientific Calculations

ScienceMark 2.0 is a benchmark based on real molecular dynamics problems. However, unfortunately, it only creates two computational threads, which has direct effect on the results. Dual-core and quad-core Intel processors perform almost equally fast here.

Following numerous requests from our readers we resumed processor testing in popular math1ematical suites, namely MATLAB and Mathematica. The latest versions of these applications are optimized for multi-threaded work.

The results of MATLAB optimization appeared quite unexpected. Although some operations (such as linear algebra, for instance) start working much faster with multi-threaded support activated, other calculations slow down. This slowing obviously affects the integral result you see on the charts for CPUs with four computational cores.

As for the Mathematica optimizations for multi-core processors, we can declare that it was pretty successful.

Gaming Applications

The only contemporary game that has fully-fledged support for quad-core processors is Supreme Commander. And you can see it very well from the results we obtained in this game. However, all other games also show that Kentsfield processors are a little faster than Conroe working at the same clock speed. It is all very simple: games are quite sensitive to the cache memory size that is why quad-core processors with two L2 caches 4MB each work faster than dual-core processors with a single 4MB cache shared between the cores.

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.

Power Consumption

The results of performance tests for Core 2 Extreme QX6850 and other processors with 1333MHz bus were quite predictable, however we can’t say the same thing about the power consumption measurements. On the one hand, the newcomer works at higher clock speed that linearly affects the power consumption, but on the other hand, it is based on the new processor stepping that Intel claims to be more power efficient. Therefore, to find out the real state of things, we decided to measure the power consumption of test systems featuring different processors.

The first measurement was made in idle mode. Enhanced Intel SpeedStep and AMD Cool’n’Quiet technologies were activated.

In idle mode Core 2 Extreme QX6850 is not really economical compared with the other solutions on Core micro-architecture. The thing is that since this CPU supports 1333MHz bus, it can only lower its frequency to 2.0GHz in case of low workload, while processors with 1066MHz bus can drop their frequency down to 1.6GHz. Although the power consumption of Core 2 Extreme QX6850 processor look still very appealing against the background of AMD processors: it turns out even more economical than AMD Athlon 64 X2 6000+.

The second session was performed with 100% CPU utilization. We used Prime95 utility for this matter.

The situation is very similar: Core 2 Extreme QX6850 is again the leader among CPU with Core micro-architecture. However, here we can also see the real advantage from the new optimized G0 processor stepping. The power consumption of the 3GHz Core 2 Extreme QX6850 processor gets really close to the results of a quad-core CPU with 2.66GHz speed based on the older processor stepping. And if we compare the power consumption of quad-core processors based on different steppings but working at the same 2.66GHz frequency, we will see that the new G0 revision allows saving about 20W in burn mode and about 5W in idle mode.


Core 2 Extreme QX6850 processor overclocking seems to be one of the most interesting topics of our today’s review. Overclockers pin their special hopes on the new G0 processor stepping. The thing is that besides lower heat dissipation, the new core may work at higher temperatures that stimulates the increase in overclocking potential.

To check out these suppositions we performed a few overclocking experiments on our Core 2 Extreme QX6850 processors. For our tests we used the already described platform based on Asus P5K Deluxe mainboard. The CPU was cooled down with a Zalman CNPS9700 LED cooler. To test the CPU and system stability during overclocking we used Prime95 utility, which new versions support multi-threading.

First of all we decided to see how far the Core 2 Extreme QX6850 processor can overclock at its nominal voltage of 1.325V for our CPU. Note that Core 2 Extreme QX6850 belongs to Extreme series, i.e. its clock frequency multiplier is unlocked. That is why we overclocked it using an increased clock frequency multiplier of 10x.

The CPU worked stably at up to 3.55GHz frequency with the Vcore at its nominal value.

This is pretty impressive overclocking result for a G0 processor stepping, especially considering that we didn’t alter its Vcore. Quad-core CPUs we tested before used to overclock to these speeds with air cooling very rarely, even with the raised core voltage.

Another great illustration of G0 processor stepping overclockability is the result we obtained after raising its Vcore to 1.45V. In this case the CPU hit the fantastic number: 3.7GHz.

So, looks like overclocking fans have every right to be impatiently waiting for the new G0 processor stepping. CPUs with this new core have every chance to become new overclocking record-breakers. With proper cooling, of course, new quad-core processors can definitely overclock better than their dual-core counterparts that have already won the computer enthusiasts’ hearts.


The results of our extensive Core 2 Extreme QX6850 test session left us with very ambiguous feelings.

On the one hand, Core 2 Extreme QX6850 didn’t please us with anything really new. The performance of this new processor was boosted with the most primitive means: higher clock speed and higher front side bus working frequency. Compared with the previous quad-core processor - Core 2 Extreme QX6800 – the newcomer offers 66MHz higher clock frequency and a processor bus with 25% higher bandwidth. Both these advantages allowed increasing the performance level of the new Core 2 Extreme QX6850 processor by 3% on average, and this improvement is hardly a real reason for celebration.

On the other hand, Core 2 Extreme QX6850 conquered an important psychological threshold. This CPU features four processor cores running at 3.0GHz. This round number looks definitely very appealing for Intel on the first Birthday of their Core based desktop processors. Especially since Core 2 Extreme QX6850 has no competitors that could get at least close to it in terms of performance. It is by far the fastest leaving behind AMD CPUs and dual-socket systems based on them.

Moreover, the official launch of Core 2 Extreme QX6850 is a sign that Intel quad-core processor will be moving to new G0 stepping. CPUs on this new stepping can boast the whole range of improvements, major being lower heat dissipation and power consumption, as well as improved overclocking potential. Core 2 Extreme QX6850 that we have discussed today is based on this particular processor stepping and can be a great choice for overclocking enthusiasts. Therefore, the only drawback of the newcomer is its relatively high price reaching $1,000.