Intel Introduces First Quad Core Processor

Intel's Quad-Core Core 2 Processor

Intel's latest creation, code-named Kentsfield, is actually not much more than an upgraded reincarnation of Intel's second generation dual-core processor which paired two single core Pentium 4 cores in one package. As seen in the image below, what Intel has done here is based on the same idea. It's easy for Intel to take two dual-core processors and attach them to one package and connect them at the northbridge.

The image below shows what an actual processor looks like without its heat-spreader. It also shows the familiar LGA775 package which this processor is built on.

So, when it comes to specs, how does the QX6700 stack up against the other offerings from Intel and AMD? As the name suggests, the QX6700 shares similar specs to the E6700. It clocks in at 2.66GHz and has 4MB L2 cache per pair of cores, for a total of 8MB of L2 cache per package. The QX6700 also utilizes a 1066MHz FSB which gives the processors access to system resources such as memory and peripherals. These specs are presented in the table below along side the specs of competitive processors.

System Configurations

If you read my review on the initial Core 2 release, you may remember that I was able to keep using Intel's D975XBX motherboard from my previous LGA775 reviews. While most people would hope and/or expect for that same convenience with this release, Intel has explicitly stated that the quad-core QX6700 will not work on the original D975XBX motherboard. For this processor, Intel has revised the board and called it the D975XBX2.

What's changed? Not a whole lot actually. The main difference, as far as the QX6700 is concerned, is revised power specifications to handle the quad-core CPU. Other than that, Intel has replaced the Silicon Image SATA controller with a Marvell Technology SATA controller, and they added an on-board power button to the right side of the board. You can see these two board below. Will your motherboard support quad-core? Check with your manufacturer for the answer to that question.

On each of these boards you will notice the heatsink is different. On the new quad-core platform Intel has provided a new, beefier fan and heatsink. This combo is designed to provide better cooling to a processor that can produce much more heat than other Core 2-based processors.

The table below outlines the configurations of my test systems. In this review I will be comparing the new QX6700 to the top Core 2 Duo, Core 2 Extreme, and AMD's top Athlon 64 FX AM2 platform. Notice that I have kept the three systems as similar as possible for testing.

The distribution and software packages were kept the same from our last review.

If your curious about my compiler optimizations, they can be found in the below table. They are pretty simple as the 64-bit version of GCC only has so many options for new processors. Most optimizations are built into the architecture flag.

Support and Stability

Once again, all systems involved in this review performed flawlessly. There was not a single crash during the testing and evaluation process. The only note on support is that the Marvell SATA controller on the D975XBX2 is fairly new and experimental in the kernel. It should be supported in a relatively new distributions but you should check with your vendor to be sure.

Performance

Let's take a look of which of our applications can benefit from the additional two cores. Some of the below benchmarks are multi-threaded while others are not. I will be sure to provide this information for each test. When an application has multi-threaded options, I always provide (number of processors) + 1 threads for the application to spawn. This assures that there should always be a waiting thread to process.

POVRay Website / POVRay Benchmark

The first benchmark stresses the floating-point capability of the processor. The stable version of POVRay that I use is not multi-threaded, but there's a version that is. I will be switching to that version upon release. The Athlon 64 still holds a strong lead in this benchmark, with the additional cores in the processors not being utilized.

Ogg Vorbis Website
Commands: oggenc input.wav, oggenc -b 192 input.wav

When encoding single audio files, you will not see too many multi-threaded applications. The Oggenc utility used here is single-threaded and does not show any benefit with the additional cores. Here the Intel processors hold the lead across the board and the higher-clocked X6800 leads the pack.

AudConvert is a Linux Hardware Application
Earlier version still used here.

AudCovert will take a directory of input files and convert them all to another format. This is a great utility if you prefer to archive in one format but need another format for a portable device. The utility is multi-threaded and can spawn as many simultaneous conversions as you want. This is an application where you will see a huge benefit for each additional core you have. Notice that the QX6700 gives an extra 40% performance here.

MPlayer/MEncoder Website
Command: mencoder merry_melodies_falling_hare.mpeg -o merry_melodies_falling_hare.avi -ovc lavc -lavcopts vcodec=mpeg4:mbd=2:vbitrate=1800:threads=# -oac copy
The video we used is freely available and can be found here at the Internet Archive.

We can use mencoder under Linux to convert one video format to another and some of the codecs provide multi-threaded options. The mpeg4 codec I used here allows you to specify the number of threads to utilize on the command line. On the QX6700, this equated to about a 30% performance decrease in encoding time. While the 15-20 seconds shown for this video may not seem like much, when encoding a full (non-copyrighted, for back-up use only) DVD, the time savings could be 15-20 minutes.

Firefox Website

Compiling using makefiles provides an easy way to utilize multiple processor cores. Using the -j# option, where # is the number of threads, you can speed up the compile time of large applications considerably. Here we see a 37% decrease in compile time from the comparably clocked E6700 to the new QX6700.

Quake 4 for Linux

Quake 4 is one of the first games to offer SMP support under Linux, so it's a great way to get some use out of an extra core. Unfortunately, Quake 4 only provides one extra execution thread, so our quad-core processor will still have two cores not being utilized. This is apparent in the graph above, since we see only a minimal gain for the quad-core processor at any resolution.

SPECViewperf Website

Our last benchmark represents workstation graphics applications but it does not seem to provide any benefit for multi-core systems. Here we continue to see a complete sweep for Intel but no extra love for the QX6700.

Power Consumption, Heat, Cost, Availability

Now we move on to some other important features of a processor when making a purchasing decision. First, let's look at how much power each of these processors can consume.

In the table above we can see the numbers published by the manufacturers and, in the graph below, we can see the numbers that I measured when benchmarking the systems.

While the Intel processors stack up as expected, the AMD processor does not seem to use as much power as they state when compared to Intel's numbers. The important thing to take away from the graph below though is that the dual-core Core 2 processors use basically the same amount of power that the Athlon 64 dual-core processors do. Due to the design of the quad-core CPU, it uses twice as much power as the dual-core counterpart, operating at the same clock-speed. As you can see, this equated to a substantial jump in energy usage when utilizing all four cores.

In the graph below, I have the temperature readings of each processor at idle and full load. While you shouldn't look too close at how these numbers compare directly to one another, due to variations in heatsinks and fans, it is important to notice that each processor is kept at a reasonable temperature by its cooling device. An important note on the low QX6700 readings is that Intel shipped the new D975XBX2 without fan control enabled, so the fan is running at 100% during testing. (They wanted to be sure heat management internal to the processor did not kick in.) I was able to adjust the fan all the way down to 60% speed though for a substantial drop in noise. With this, I only saw an increase in idle and load temp of 1º C and 4º C respectively and a power usage drop of about 10 W. These temperatures are very impressive given the power draw of the processor, and shows again the efficiency of the Core 2 design.

Finally, let's look at the price and availability of each processor reviewed, at time of publication, in the table below.

All of the previously announced processors are readily available from both system vendors and as boxed processors. The new Core 2 Extreme QX6700 should be available in 2-3 weeks according to Intel. As far as cost goes, you truly pay a premium for the “Extreme” line of Core 2 processors. At around $440 more than the E6700, the X6800 is a hard sell with only additional clock speed boost and an unlocked multiplier. The price boost on the QX6700 may be worth it if though you have an application that can truly benefit from more than two cores or if you do that much multi-tasking. The Athlon 64 FX-62 is priced somewhere in the middle of the pack but unfortunately offers no real advantage over a Core 2-based processor.

The Bottom Line

The Core 2 Extreme QX6700 is a leap in multi-core processor design with the growth of processor cores advancing by powers of two for the foreseeable future. If you have applications that can take advantage of more than two cores, the QX6700 will definitely not let you down in the performance department. The application support is the problem with the QX6700. It is actually a little ahead of its time for desktop and even workstation users. There are still only a few programs that benefit from the extra cores. There is a lot of development work going into making many existing and future versions of software multi-threaded, but we are still a little ways from the release of these applications. Even game developers are working on adding support for two or more cores, but many of these games will not be available until next year. I give props to Intel for this bold release and for not playing the “chicken and egg” game with software vendors. This QX6700 is everything a first generation quad-core processor should be and the numbers show this when the application can take advantage of what Intel is providing.