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Intel Core 2 Extreme QX6800
Date: Apr 08, 2007
Author: Marco Chiappetta
Introduction and Related Information

Hot on the heals of the holiday weekend, Intel is launching a new flagship quad-core processor targeted at hardcore power users and PC enthusiasts. As its name implies, the new Core 2 Extreme QX6800 has frequency parity with its dual-core counterpart, the Core 2 Extreme X6800 - sans the "Q". At 2.93GHz this makes the Core 2 Extreme QX6800 Intel's highest clocked quad-core desktop processor to date.

Other than its higher frequency though, the Core 2 Extreme QX6800 doesn't differ from Intel's previous high-end quad-core processor, the 2.66GHz Core 2 Extreme QX6700, in any way. But what the QX6800's higher core frequency offers is an answer to any performance advantage the higher clocked X6800 had when running single-threaded applications.

To see just how much power the new Core 2 Extreme QX6800 had lurking under its unassuming heat spreader, we installed one into a 975X-based test bed an took it for a spin. Read on to see how it did. Just hide your tax return or your going to want to give Big Blue a big chunk of what Uncle Sam just gave back.

Intel Core 2 Extreme QX6800 Processor
Specifications & Features
  • Core Frequency -  2.93GHz
  • System Bus Frequency - 1066 MHz
  • TDP (Thermal Design Power) -  130W   
  • Stepping   B-3     
  • Number of CPU Cores -  4       
  • L2 Cache - 8MB (2 x 4 MB)    
  • Core to bus ratio limit 10:1   
  • Max processor input voltage (VID) - 1.350V
  • .065-micron manufacturing process
  • Shared Smart Cache Technology
  • PECI Enabled 
  • Enhanced Intel SpeedStep Technology (EIST)     
  • Extended HALT State (C1E) Enabled       
  • Execute Disable Bit (XD) Enabled          
  • Intel 64 Technology       
  • Intel Virtualization Technology (VT)     
  • Package / Socket -  Flip Chip LGA775       
  • Combined Die Size: Approximately 286 mm2
  • Approximately 582M Transistors
  • MSRP - $999

Core 2 Extreme QX6800

Over the course of the past year or so, we have posted a wealth of information related to Intel's Core microarchitecture and Core 2 Duo and Extreme processors here at HotHardware.com. For more background on the technologies employed by the Core microarchitecture and Intel's platform as a whole, we suggest taking a look at few of these related articles.  They contain detailed explanations of some of the features common to Intel's legacy products, compatible chipsets, and the new Core 2 Duo and Core 2 Extreme processors:

We cover some specifics regarding Intel's 65nm manufacturing process in our 955XE / i975X evaluation and outline Intel's AMT (Active Management Technology) and IVT (Intel Virtualization Technology), among other things inherent to the Core microarchitecture, in our Core 2 Duo E6700 & Extreme X6800 Evaluation .  The other articles listed above will also give you some background as to how the Core 2 has matured these last few months, leading up to today's official launch of the new quad-core Core 2 Extreme QX6800 processor.

Beyond the clock speed bump, there really isn't too much more to know about the QX6700 versus the QX6700 or X6800, other than the fact that the chip is simply a pair of dual-core, Core 2 Extreme X6800 processor cores clocked at 2.93GHz, on a single package substrate, sharing a single 1066MHz QDR (Quad Data Rate) System Bus.  That's four cores and 8MB of on-die cache all in a single LGA775 socket.  In other words, double the cores, and double the cache of Intel's high-end Core 2 Duo dual-core processors.  Of course that also takes the QX6800's TDP (Thermal Design Power) up a notch from the Core 2 Duo's 65-75 Watt range to roughly double that at 130 Watts.  This puts this new Intel quad-core CPU within range of Intel's legacy Pentium Extreme Edition 965 dual-core chip from a power and heat dissipation perspective.  That's not too bad when you consider how much faster the architecture has proven itself to be and the fact that we're talking four cores in total here, versus only two in the Pentium EE 965.

Vital Signs and Overclocking

Prior to benchmarking the new Core 2 Extreme QX6800, we spent some time with CPU-Z to see if there was anything interesting to report in regard to the CPU's default configuration. We then took some notes on temperatures and overclocking as well.



CPU-Z: Core 2 Extreme QX6800

Other than the Core 2 Extreme QX6800's clock speed, nothing much has changed since we last looked at the QX6700 a few months back. As you can see, both processors are based on the same B3 core stepping. The new QX6800 processor is also built using Intel's 65nm manufacturing process and it is clocked at 2.93GHz (11x266MHz), with 4MB of L2 cache per dual-core die, for a total of 8MB of L2 cache. There is also 128K of L1 cache (64K x 2) per execution core, for a total of 256K of various types of L1 cache (32K instruction and 32K data caches, per core).

Overclocking the Core 2 Extreme QX6800
Making The Fastest, Even Faster...


Core 2 Extreme QX6800 Overclocked to 3.43GHz

After our initial inspection, we spent some time overclocking the new Core 2 Extreme QX6800 and had some interesting results. To overclock the processor, we used Intel's stock aluminum / copper PIB cooler. We bumped the CPU voltage up to 1.4v and set the memory voltage to 2.2v. We left the processor's multiplier at its stock value of 11x and raised the front side bus frequency until the test system was no longer stable.

In the end, we were able to take the QX6800 to just under 3.5GHz with an FSB of 312MHz. The approximate 500MHz overclock equates to roughly a 17% increase in clock speed, which respectable considering the mild voltage increase and the fact that we were using stock cooling. We were able to boot into Windows at speed approaching 3.6GHz, but we couldn't keep the system stable. Perhaps with more elaborate cooling and some more voltage, we would have had better luck.

We would also like to note that through all of our preliminary tests, we monitored the processor's temperatures via Intel's Desktop Control Center software. While idling at stock speeds, we found that the Core 2 Extreme QX6800 processor's core temperature hovered around 42oC. And under load temperatures peaked at around 64oC. Overclocking the CPU to almost 3.5GHz didn't drastically effect temperatures, but we did see a max of about 70oC at one point, at least according to Intel's Desktop Control Center software.

Our Test Systems and SANDRA XI SP1

How we configured our test systems: When configuring our test systems for this article, we first entered their respective system BIOSes and set each board to its "Optimized" or "High Performance Defaults". We then saved the settings, re-entered the BIOS and manually set the memory for DDR2-800 operation with 4,4,4,12 timings. The hard drives were then formatted, and Windows XP Professional (SP2) was installed. When the Windows installation was complete, we installed the drivers necessary for our components, and removed Windows Messenger from the system. Auto-Updating and System Restore were then disabled and we set up a 1024MB permanent page file on the same partition as the Windows installation. Lastly, we set Windows XP's Visual Effects to "best performance," installed all of our benchmarking software, defragged the hard drives, and ran the tests.

HotHardware's Test Systems
AMD & Intel Inside!
System 1:
Core 2 Extreme QX6800
(2.93GHz - Quad-Core)
Core 2 Extreme QX6700
(2.66Hz - Quad-Core)
Core 2 Extreme X6800 / E6700
(2.93GHz & 2.66GHz)

Intel D975XBX2
(975X Express)

2x1GB Corsair PC-6400
CL 4-4-4-12 - DDR2-800

GeForce 7950 GX2
On-Board Ethernet
On-board Audio

WD740 "Raptor" HD
10,000 RPM SATA

Windows XP Pro SP2
Intel INF
NVIDIA Forceware v91.27
DirectX 9.0c

System 2:
AMD Athlon X2 6000+

Athlon 64 FX FX-62

Asus M2N32-SLI Deluxe
(NVIDIA nForce 590 SLI)

2x1GB Corsair PC-6400
CL 4-4-4-12 - DDR2-800

GeForce 7950 GX2

On-Board Ethernet
On-board Audio

WD740 "Raptor" HD
10,000 RPM SATA

Windows XP Pro SP2
nForce Drivers v9.35
NVIDIA Forceware v91.27
DirectX 9.0c

System 3:
AMD Athlon 64 FX-74
AMD Athlon 64 FX-72
AMD Athlon 64 FX-70

(3.0GHz, 2.8GHz, 2.6GHz)

Asus L1N64-SLI WS
(NVIDIA nForce 680a SLI)

4x512MB Corsair PC-6400
CL 4-4-4-12 - DDR2-800

GeForce 7950 GX2

On-Board Ethernet
On-board Audi

WD740 "Raptor" HD
10,000 RPM SATA

Windows XP Pro SP2
nForce Drivers v9.53
NVIDIA Forceware v91.27
DirectX 9.0c

Preliminary Testing with SiSoft SANDRA XI
Synthetic Benchmarks

We began our testing with SiSoftware's SANDRA XI, the System ANalyzer, Diagnostic and Reporting Assistant. We ran six of the built-in subsystem tests that partially comprise the SANDRA XI suite with the Core 2 Extreme QX6800 (CPU, Multimedia, Multi-Core Efficiency, Memory, Cache, and Memory Latency). All of the scores reported below were taken with the processor running at its default clock speeds of 2.93GHz.

Core 2 Extreme QX6800 @ 2.93GHz
CPU Arithmetic

Core 2 Extreme QX6800 @ 2.93GHz

Core 2 Extreme QX6800 @ 2.93GHz
Multi-Core Efficiency

Core 2 Extreme QX6800 @ 2.93GHz
Memory Bandwidth

Core 2 Extreme QX6800 @ 2.93GHz
Cache and Memory

Core 2 Extreme QX6800 @ 2.93GHz
Memory Latency

The Core 2 Extreme QX6800 performed just as you'd expect it would in the various SANDRA subsystem tests. In the CPU and Multimedia benchmarks, it was clearly the fastest of the bunch thanks to its higher frequency. The Multi-Core Efficiency benchmark had it finishing behind a high-end Xeon rig, and in the Memory Bandwidth, Memory Latency, and Memory and Cache benchmarks, the QX6800 finished in-line with other similarly configured Intel-based reference systems.

PCMark05: CPU and Memory

For our next round of synthetic benchmarks, we ran the CPU and memory performance modules built into Futuremark's PCMark05 suite. 

Futuremark PCMark05
More Synthetic CPU and Memory Benchmarks

"The CPU test suite is a collection of tests that are run to isolate the performance of the CPU. The CPU Test Suite also includes multithreading: two of the test scenarios are run multithreaded; the other including two simultaneous tests and the other running four tests simultaneously. The remaining six tests are run single threaded. Operations include, File Compression/Decompression, Encryption/Decryption, Image Decompression, and Audio Compression" - Courtesy FutureMark Corp.


Thanks to its four cores and high frequency, the Core 2 Extreme QX6800 finished at the head of the pack in PCMark05's CPU performance module. In a synthetic, multi-threaded benchmark like this, that can fully exploit the processor's capabilities, being the highest clocked quad-core Core 2 processor, makes it the fastest CPU here by a significant margin.

"The Memory test suite is a collection of tests that isolate the performance of the memory subsystem. The memory subsystem consists of various devices on the PC. This includes the main memory, the CPU internal cache (known as the L1 cache) and the external cache (known as the L2 cache). As it is difficult to find applications that only stress the memory, we explicitly developed a set of tests geared for this purpose. The tests are written in C++ and assembly. They include: Reading data blocks from memory, Writing data blocks to memory performing copy operations on data blocks, random access to data items and latency testing."  - Courtesy FutureMark Corp.

Our Core 2 Extreme QX6800 powered test bed finished just just in front of the QX6700 in PCMark05's Memory Performance module, but the delta separating the two processors is relatively small. Because the memory controller resides in the chipset's northbridge, and the QX6800 and QX6700 utilize the same chipset here and have the same FSB and memory frequencies, you can expect them to put up similar scores in memory related benchmarks.

Office XP and Photoshop 7

PC World Magazine's Worldbench 5.0 is a business and professional application benchmark.  The tests consist of a number of performance modules that each utilize one, or a group of popular applications to gauge performance. 

Worldbench 5.0: Office XP SP2 and Photoshop 7 Modules
Real-World Application Performance

Below we have the results from WB 5.0's Office XP SP2 and Photoshop 7 performance modules, recorded in seconds.  Lower times indicate better performance here, so the shorter the bar the better.


The Core 2 Extreme QX6800 processor put up the best scores in the two Worldbench 5.0 tests we ran. In the Office XP test, the QX6800 bested the QX6700 and X6800 processors by 9 and 3 seconds, respectively.  And in the Photoshop test its leads over the same two processors were 14 and 4 seconds.

LAME MT and Sony Vegas

In our custom LAME MT MP3 encoding test, we convert a large WAV file to the MP3 format, which is a very popular scenario that many end users work with on a day-to-day basis to provide portability and storage of their digital audio content. 

LAME MT MP3 Encoding Test
Converting a Large WAV To MP3

In this test, we created our own 223MB WAV file (a never-ending Grateful Dead jam) and converted it to the MP3 format using the multi-thread capable LAME MT application in single and multi-thread modes. Processing times are recorded below. Once again, shorter times equate to better performance.


Although its clock speed is similar to the Core 2 Extreme X6800, the new QX6800 trailed the flagship dual-core processor by a couple of seconds in the multi-threaded portion of this test, which we should note run in only two threads maximum.  In single threaded mode, the two chips performed identically, but in MT mode - likely due to contention for resources or Windows scheduling issues - the QX6800 falls slightly behind.

Sony Vegas Digital Video Rendering Test
Video Rendering Performance

Sony's Vegas DV editing software is heavily multithreaded as it processes and mixes both audio and video streams. This is a new breed of digital video editing software that takes full advantage of current dual and multi-core processor architectures.

The Core 2 Extreme QX6800 put up the best score in the Sony Vegas benchmark, outpacing the previous champion QX6700 by about 9 seconds. The pseudo quad-core Quad FX rigs put up a good fight here as well, but the Intel chips still held onto a sizable lead.

Cinebench v9.5 and 3DMark06 CPU

The Cinebench 9.5 benchmark is an OpenGL 3D rendering performance test, based on the commercially available Cinema 4D application. Cinema 4D from Maxon is a 3D rendering and animation tool suite used by animation houses and producers like Sony Animation and many others. And of course it's very demanding of system processor resources.

Cinebench 9.5 Performance Tests
3D Modeling & Rendering Tests

This is a multi-threaded, multi-processor aware benchmark that renders a single 3D scene and tracks the length of the entire process. The time it took each test system to render the entire scene is represented in the graph below (listed in seconds).

In the single-threaded portion of this test, the Core 2 Extreme QX6800 puts up the second best score, missing the mark set by the dual-core X6800 by 1 second. However, in multi-threaded mode in which all four execution cores are utilized, the new QX6800 pulls ahead of every other configuration. The one second difference may not look like a large margin, but if we talk in percentages, that one second equates to a healthy 6.6% lead over the QX6700.

Futuremark 3DMark06 - CPU Test
Simulated DirectX Gaming Performance

3DMark06's built-in CPU test is a multi-threaded "gaming related" DirectX metric that's useful for comparing relative performance between similarly equipped systems.  This test consists of two different 3D scenes that are generated with a software renderer that is dependent on the host CPU's performance.  This means that the calculations normally reserved for your 3D accelerator are instead sent to the central processor.  The number of frames generated per second in each test are used to determine the final score.

The quad-core configurations clearly lead the pack here, with the new Core 2 Extreme QX6800 firmly entrenched in the top spot with a score roughly 210 points higher than the second place finisher, the QX6700. The QuadFX rigs finish in the third, fourth, and fifth positions, followed by the dual-core configurations.

Quake 4: Low and High Resolutions

For our next set of tests, we benchmarked all of the test systems using a custom single-player Quake 4 timedemo. Here, we installed the game's official v1.3 point release which is SMP capable and ran the benchmark in two different configurations.  First, we turned the resolution down to 640x480, and configured the game to run at its "Low-Quality" graphics setting. Although Quake 4 typically taxes today's high-end GPUs, when it's configured at these minimal settings, it is much more CPU and memory bandwidth-bound than anything else. Then we upped the resolution to 1600x1200 and enabled 4X anti-aliasing and anisotropic filtering to see how the platforms compared in a more taxing gaming environment.

Benchmarks with Quake 4 v1.3
OpenGL Gaming Performance


In out custom low-res Quake 4 benchmark, the highest clocked Intel processors, the 2.93GHz QX6800 and X6800 processors, finished in the top two positions, followed by the 2.66GHz QX6700 and E6700 CPUs.  However, the trend is muddled by the quad and dual-core nature of the processors. This high resolution benchmark does a better job at clearly defining a performance leader. Here, the new QX6800 takes the pole position, followed in order by the other Intel-built processors.

F.E.A.R.: Low and High Resolutions

For our last set of game tests, we moved on to more in-game benchmarking with F.E.A.R. When testing processors with F.E.A.R, we drop the resolution to 640x480, and reduce all of the in-game graphical options to their minimum values to isolate CPU and memory performance as much as possible.  However, the in-game "effects" and "advanced computer options" settings, which control the level of detail for F.E.A.R.'s physics engine and particle system, are left at their maximum values, since these actually do place some load on the CPU rather than GPU. Like we did with Quake 4 on the previous page, we also ran a set of number with F.E.A.R. running at high-resolution with additional pixel processing enabled to asses performance in a typical high-end gaming scenario.

Benchmarks with F.E.A.R. v1.08
DirectX 9 Gaming Performance


The low-res versus high-res performance trend with F.E.A.R. is exactly the opposite of the Quake 4 results on the previous page. With F.E.A.R. running in low-resolution/low-quality mode, the quad-Core Intel processors jump out to a commanding lead, specifically the QX6800 which is the only chip to break the 300FPS mark. Conversely, with the game running in a more demanding high-resolution/high-quality mode, which heavily taxes the graphics subsystem, the graph levels out and only a couple of frames per second separate the different configurations.

Power Consumption

We have one final data point we'd like to cover before bringing this article to a close. In this section, our goal was to give you all an idea as to how much power each of the system configurations we tested used while idling and running under load.

Power Characteristics
Processors and Platforms

Please keep in mind that we were testing total system power consumption at the outlet, in these tests, not just the power being drawn by the processors alone.  In this test, we're showing you a ramp-up of power from idle on the desktop to full CPU load.  We tested with a combination of Cinebench 9.5 and SANDRA XI running on the CPU.

As you'd expect from a processor running 266MHz higher than its similarly outfitted counterpart, the new Core 2 Extreme QX6800 consumes more power than the QX6700. Somewhat surprisingly, the QX6800 also consumed a bit more power while idling, despite the fact that both processors drop down to a similar low-speed state when not in use.  We'll have to chalk up the 6 watt delta while idling to voltage fluctuations and slight differences in the processors due to being manufactured at different times. While under load, however, the approximate 20 more watts consumed by the QX6800 can be attributed to its higher frequency. What is also interesting to note is that the dual-core Athlon 64 X2 6000+ consumed almost as much power under load than Intel's quad-core offerings.  AMD is going to have to transition the manufacturing of their high-end processors to the company's 65nm process node to bring power consumption in-line with Intel at the high-end.  For their lower-speed chips, AMD has already done so, and relatively lower-wattage processors from AMD are already available.

Our Summary and Conclusion

Performance Summary: Simply put, the new Core 2 Extreme QX6800 is the fastest, most powerful desktop PC processor we have tested to date. Due to its 2.93GHz clock speed, which matches that of the fastest dual-core Core 2 processor, the X6800, the new QX6800 is as fast as the X6800 while running single-threaded applications, as is the case with most game engines and office productivity tools. While running multi-threaded applications that can fully utilize the additional processing resources afforded by the quad-core design of the QX6800 however, the new Core 2 Extreme QX6800 clearly offers more performance than any other desktop PC platform currently available. Performance scaling isn't always 2x that of the dual-core X6800 when running multi-threaded applications, but the quad-core Core 2 Extreme QX6800 does offer significant performance increases in many scenarios. And as more and more multi-threaded applications are released, the advantages of a quad-core processors will pay dividends over time. 


While the launch of the Core 2 Extreme QX6800 is technically nothing more than a speed bump of an already established design, it is still significant none-the-less. What Intel has done with the QX6800 is bring their flagship quad-core desktop processor up to the same frequency as their fastest dual-core offering. By doing so, any performance disadvantage the 2.66GHz Core 2 Extreme X6700 had versus the higher clocked 2.93GHz Core 2 Extreme X6800, while running single-threaded code, is now absorbed. Conversely, any advantage Intel's quad-core processors had over their dual-core offerings, or AMD's for that matter, is even more amplified. Ultimately, what the new Core 2 Extreme QX6800 represents is the best of both worlds.  Aside from its exorbitant $1200 price tag, which is high even for top-of-the-line Extreme Edition processors, the Core 2 Extreme X6800 is a no compromise solution. Its thermal profile and power consumption were in-line and its overall performance was superb. If you're a PC enthusiast looking for nothing less than the highest performing desktop processor, look no further - the Core 2 Extreme QX6800 is it. What more is there to say?

  • Great Performance
  • Fastest Desktop CPU to Date
  • Manageable Power and Thermal Requirements
  • Overclocking Headroom
  • Expensive!
  • Shared FSB

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