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Closer Look at Athlon II X4

All AMD processors using four computational cores have always been manufactured within Phenom and Phenom II families. Moreover, the Phenom brand name was also used for some triple-core and dual-core. As a result, the Athlon brand name became a symbol for budget solutions. Obviously, by launching their new Athlon II X4 family, AMD appeals to the same exact associations: Athlon II X4 processors should become the most affordable quad-core CPUs in the market selling for about $100-$120.

As a result, this is what the full list of AMD offering will look like now:

Note that besides the fact that 45 nm AMD processors have different names, the model numbers are part of the single system. For example, quad-core Athlon II X4 processors belong to 600 series, while Phenom II X4 are assigned to 800 and 900 series.

Although Athlon II X4 processors are about 1.5-2 times cheaper than Phenom II X4, they don’t have any serious microarchitectural differences. In fact, Athlon II X4 is the same Phenom II X4 but without the shared 6MB L3 cache and with slightly lower clock speeds. However, it is exactly the elimination of L3 cache seeming not too serious for the performance that has the biggest effect on AMD’s production costs. The thing is that L3 cache memory in Phenom II X4 processors occupies one third of the processor die. Therefore, by physically removing L3 cache from the semiconductor die, AMD can lower the production cost significantly and as a result, reduce the end price on the retail products.

To illustrate everything we have just pointed out above, let me offer you a table summing up the major specifications of quad-core AMD processors. For a more illustrative picture included are also the old previous-generation quad-core solutions based on 65 nm cores.

As we see, AMD managed to reduce the die size of Athlon II X4 processors to 169 mm2. And this is a great result allowing the company to start the price war against Intel without any reservations. The junior quad-core Intel CPUs from the Core 2 Quad Q8000 series consist of two semiconductor dies, each 82 mm2 big. So, the production cost of an Athlon II X4 processor is about the same as the production cost of Core 2 Quad Q8000, which gives AMD a lot of freedom in price manipulations.

At the same time AMD didn’t want to allocate any engineering resources for major core redesign. The “Athlon II X4 = Phenom II X4 – L3 cache” formula is true not only in respect to CPU characteristics. It can also be seen in the core structure. You can see from the photo of the Propus semiconductor die that the part with L3 cache memory has simply been cut off:

Phenom II X4 (Deneb) - on the left, Athlon II X4 (Propus) - on the right

It is absolutely clear from what has been just said that Athlon II X4 processors do not have any undocumented features for L3 cache activation, which a lot of enthusiasts have been secretly hoping for. There is simply no L3 cache that is why in a general case you can’t turn Athlon II X4 into a Phenom II X4.

However, there are a few exceptions. As we learned from one of our AMD contacts, some Athlon II X4 SKUs will be based on Deneb core with a disabled L3 cache that is why if you are lucky, you may still be able to transform your Athlon II X4 into a Phenom II X4. Of course, although Phenom II X4 800 series has been discontinued, AMD still wants to have the opportunity to use partially defective  semiconductor dies left from the production of higher-end processor models. And Athlon II X4 will be exactly this opportunity for them.

Athlon II X4 model lineup will include two solutions with 620 and 630 model numbers. The CPU clock speeds will be 2.6 and 2.8 GHz respectively. Their more detailed specifications are given in a small table below:

AMD plans to launch more Athlon II X4 CPU models. Within the next few quarters the clock speed of the top processors in this lineup will reach 3.0 GHz. There will also be energy-efficient CPU modifications with 45 W thermal design power.

In conclusion to our brief introduction of the new Athlon II X4 processors let us offer traditional screenshots from CPU-Z utility confirming all processor specifications mentioned above:

Note that the CPUID indicator of the new processors has a 00100F52h number that hasn’t been used before, which confirms the uniqueness of these CPU dies and absence of any L3 cache memory in them. The potentially “lucky” Athlon II X4 processors based on defective Deneb cores should have “4” as a model number. This will allow distinguishing them from the other processors based on Propus semiconductor dies.

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