AMD Phenom II X4 840 & X4 975 Black Edition Processors Review

Author: MAC
Date: January 3, 2011
Product Name: AMD Phenom II X4 840 / 975 Black Edition Processor
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Phenom II X4 840 & X4 975 Black Edition Specs

Deneb Die vs. Propus Die - L3 cache takes up a lot of die space

As enthusiasts await the launch of the much hyped Bulldozer microarchitecture, AMD have been keeping everyone distracted with a constant stream of new Athlon II and Phenom II processor models. In September alone they released the Phenom II X6 1075T, Phenom II X4 970 BE, Phenom II X2 560, Athlon II X4 645, Athlon II X3 450, and Athlon X2 265. Subsequently, less than one month ago, they unveiled the flagship six-core Phenom II X6 1100T, the Phenom II X2 565 Black Edition, and the Athlon II X3 455. Today, AMD are unleashing two additional quad-core models, the enthusiast-oriented Phenom II X4 975 Black Edition, and a value-oriented model in the form of the $102 3.2Ghz Phenom II X4 840.

Usurping the only 2 month old Phenom II X4 970 BE, the new X4 975 Black Edition now holds the title of the most highly clocked processor that AMD has ever produced. It is intended for overclockers and those who want the best possible performance in today's applications, most of which can't utilize more than 4 cores. This new model only costs $9 more than the previous X4 970, quite reasonable, but it is also only $5 cheaper than the X6 1075T, and we suspect that many are going to be swayed into paying the slight price premium in order to gain two additional cores.

After a long hiatus, we were admittedly surprised to see a brand new Phenom II X4 800-series model, and even more surprised that this new model featured no L3 cache. This in effect puts the X4 840 in the same class as the de-cached Athlon II X4 processors. We suspect that this model is based on the Athlon II X4's L3 cache-less Propus die, and not simply made up of Deneb cores with defective L3 cache. It will be very interesting to find out whether the additional clock speed is sufficient to overcome the significant deficit caused by the cache reduction. This potential shortcoming will likely make itself evident in games, so definitely keep an eye on that.

As our media samples come packaged differently, you can expect the Phenom II X 975 Black Edition and Phenom II X4 840 to ship in these respective boxes. Unchanged from previous Phenom II Black Edition and Phenom II models.

As you can see, both of these chips were manufactured in the 39th week of 2010. That is a full month later than our Phenom II X6 1110T sample. That's 4 weeks of potential manufacturing process improvements, which might equate to improved overclocking headroom and lower operating temperatures. If you are anxious to find out how these chips fared, check out our Overclocking Results section.

Obviously, both of these chips are based on the 938 pin AM3 socket. The longevity of the AM3 form factor, and potential for backwards compatibility with AM2+, has consistently been a main factor in keeping AMD's processors attractive and relevant when compared to Intel's generally faster offerings.

As we suspected, the "BL-C3" revision for the Phenom II X4 840 signifies that it is in fact based on the Propus die used in Athlon II X4's. The Phenom II X4 975 uses the familiar C3 revision that was unveiled all the way back in November 2009.

Nothing surprising on the northbridge frequency front, just the same 2000Mhz as all previous Athlon II/Phenom II chips. We would love to see AMD increase this to 2200Mhz or 2400Mhz since it would have a considerable impact on overall performance.

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