Intel's Core 2 Extreme QX6700: The Multi-core Era Begins

Performance per Watt Comparison

3dsmax 7

3dsmax, like many 3D renderers, absolutely loves more cores and here we see Kentsfield maintain a tremendous performance advantage over Conroe. The scores reported are the SPECapc 3dsmax rendering composite in points, higher numbers being better, but the most interesting values are the performance per watt numbers.

Note: we are looking at system power draw rather than trying to isolate just the CPU. In that sense, we are comparing potential of running quad core configurations - i.e. in render farms and the like - instead of more dual core systems. Were we to get just the CPU power usage numbers, we would expect the usage of two identical cores in a single package to basically double power draw.

With higher performance and higher power consumption, the two manage to balance out and result in better performance per watt out of the two Kentsfield based parts than any of the dual core CPUs. While Kentsfield does require more power than Conroe, you get an even larger increase in performance thus resulting in a more efficient overall CPU.

Let's see if this is the start of a trend...

Cinebench 9.5

The Cinebench 9.5 test is also a multithreaded 3D rendering benchmark that will take advantage of as many cores as are present in the system. For each core, Cinebench spawns an additional renderer to help speed up the rendering of a static scene. Performance goes up by over 60% when moving from two to four cores, but once again it's the performance per watt that is particularly interesting:

None of the dual core CPUs can come close to touching the power efficiency of the quad core Kentsfield based offerings.

DivX 6.1

Media encoding applications were the first to get a performance boost from dual core CPUs, but the impact is not nearly as great when we move to quad core processors. There's a gain of around 38%, which is by no means bad, just simply not as great as what we saw in the previous 3D rendering tests. The end result is that performance per watt is a lot closer between the most efficient dual core CPUs and the new quad core offerings:

If we look at performance per watt per transistor, Kentsfield is really not doing well here at all, despite an increase in performance and a continued advantage in performance per watt.

Windows Media Encoder 9

We see a much stronger showing from Kentsfield in the WME9 test, indicating that the DivX test was not representative of all media encoding on quad core.

Quicktime (H.264)

Interestingly enough, our Quicktime H.264 test didn't show any performance improvement going from two to four cores, indicating that the encoding process is optimized for two threads. Quicktime thus becomes the posterchild for what's necessary for the multicore revolution to truly bring about greater power efficiency: better threading within applications.

Here the dual core offerings are clearly superior when it comes to performance per watt simply because the Kentsfield CPUs aren't able to outperform them, all while using more power. The efficiency wouldn't be a problem if Kentsfield was able to power down unused cores independently of one another.

iTunes MP3

Our final test is yet another benchmark that only spawns two encoding threads, and we get another example of how power efficiency falls off if the software is not threaded enough to match the CPU's resources.