Intel is going to release their first quad-core desktop CPU in next November under the Core 2 Extreme series and in January 2007 mainstream quad-core CPUs will be released as Core 2 Quad. Let’s take a look at the technology and specs used by these new CPUs.

First we need to talk about how multi-core CPUs are built. There are two approaches. On the first one, called “multi-chip”, each core is made by different chips that are put together in a single package. Pentium D is a good example of a dual-core CPU that uses this approach. On CPUs based on this technology when one of the CPU cores wants to talk with the other, it needs to go outside the CPU package, i.e., use the front side bus. Also the L2 memory cache is separated, thus when one core wants to access data stored on the cache of the other core, it need to access it through the front side bus. Of course using the front side bus isn’t the best option, as the CPU runs internally faster than then front side bus.

The second approach is called “monolithic”. Here the cores are already manufactured in only one chip. This is the technology used by Core 2 Duo CPUs, for example. When the CPUs want to talk to each other they don’t need to use the front side bus, as they were already built stuck together. Also, under this technology the memory cache is shared between the two cores. Performance wise this is the best option.

In Figure 1 you see a summary of what we’ve just explained.

Intel Quad-Core CPUFigure 1: The two available approaches for building multi-core CPUs.

The new quad-core CPUs from Intel will mix both technologies. They will have two monolithic dual-core chips installed together in a single package. This means that cores 1 and 2 share the same memory cache, the same happening with cores 3 and 4. If cores 1 or 2 needs to talk with core 3 or 4 or to access the other cache, they will need to this externally, i.e., using the front side bus – which on the first models will be of 1,066 MHz. We drew a diagram illustrating this in Figure 2.

Intel Quad-Core CPUFigure 2: Intel approach for their first quad-core CPUs.

In November Intel will launch their first quad-core desktop CPU, called Core 2 Extreme QX6700. As you can see, it will be released under the Core 2 Extreme series, using the letter “Q” to indicate that it is a quad-core CPU. It will run at 2.66 GHz with a 1,066 MHz external bus, 8 MB total L2 cache (4 MB x 2) and will come with its overclocking protecting unlock, following the tradition of Intel’s Extreme series. The other specs continue to be the same as the rest of the Core 2 Duo family.

Intel Quad-Core CPUFigure 3: Core 2 Extreme QX6700 main specs.

On the same timeframe Intel will release their first quad-core Xeon CPU, Xeon 5300.

In January 2007 Intel will release Core 2 Duo CPUs with four cores and they will be named Core 2 Quad. So far Intel didn’t tell us what the models would be released. In the same timeframe Intel will also release a low voltage quad-core Xeon, which promises to dissipates 40% less power.

As for quad-core performance, we will be posting something about it during this week.