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AMD's Phenom II X4 955 processor

...Black Edition

Ah, progress. As we hurtle forward in time, developing minor medical conditions and growing hair in weird places, the chips inside our computers get ever better—or such is the usual way of things. Sometimes progress comes in big leaps, as it did with the debut of Intel's Core i7 processors not so long ago, and sometimes it comes in smaller increments, as it has with AMD's Phenom II processors in the several months since their first introduction. The latest waystation on the way to, er, CPU nirvana is being unveiled today in the form of the Phenom II X4 955.

The X4 955 is the culmination of a process in which we saw the Phenom II first hit the market and then, a month later, transition to Socket AM3 and gain compatibility with DDR3 memory. Those first Socket AM3 processors were mainstream offerings, with smaller caches, lower clock speeds, and fewer cores than the top-of-the-line products. Today, in the form of the X4 955, AMD brings to market a true flagship for its new lineup. This is a quad-core processor with a full 6MB of L3 cache and the highest clock frequency to date for a Phenom II: 3.2GHz.

Since this is a Socket AM3 processor, it's compatible with both Socket AM3 motherboards that support DDR3 memory and Socket AM2+ motherboards that use DDR2 memory. And since this is a new flagship for AMD, the 955 is a "Black Edition" processor with all of the privileges that title bestows—pretty much just "easy overclocking via an unlocked multiplier," but hey, that's not a bad perk.

The 955 isn't the only new horse in AMD's stable, either. There's also its younger sibling, the Phenom II X4 945, which runs at 3GHz and doesn't have the distinction of being a Black Edition product, either. Instead, the 955 gets all the glory, and the 945 keeps to itself and spends a lot of time in its room reading comic books. Here are the highlights of both new models, for comparison:

Model Clock speed North bridge/
L3 cache speed
L3 cache
Cores TDP Price
Phenom II X4 955 Black Edition 3.2 GHz 2.0 GHz 6MB 4 125W $245
Phenom II X4 945 3.0 GHz 2.0 GHz 6MB 4 125W $225

As you can see, the 945 is only 20 bucks cheaper than the 955, and I'd say paying a little more for that unlocked multiplier in the Black Edition is worth it every time, unless the very idea of overclocking causes you to break out in sweats or evokes deep feelings of shame. Still, neither CPU is particularly expensive for a processor at the top of AMD's lineup. The firm has made a commitment to remain competitive with Intel on price and performance, and the 955's $245 price tag would appear to position it against the Core 2 Quad Q9550, a 2.83GHz chip with four cores and 12MB (or, more precisely, 2 x 6MB) of L2 cache. Intel's current price list has the Q9550 at $266, so the Phenom II X4 955 undercuts it a little bit, in fact.

One place where Intel may have a bit of an advantage, though, is in the power consumption department. The Q9550 has a TDP rating of 95W, while AMD has rated the X4 955 at 125W. TDP is a peak number, so those ratings really only apply when the processor is fully occupied. Still, even now, AMD's best processors may need a little more thermal headroom to match the equivalent Core 2 Quads.

AMD's stock cooler for retail boxed versions of the Phenom II X4 955

Speaking of thermal envelopes (guys: use this transition line on your next date—pure dynamite), here's a look at the stock heatsink/fan combo AMD supplies with retail boxed versions of the X4 955. Not a total beast, at least, and fairly similar to any number of past stock AMD models, which are usually pretty decent coolers. We opted instead for an aftermarket cooler with a prop the size of a small aircraft, to enable quiet and copious overclocking.

We have, of course, a huge collection of CPU performance results, and we've run the X4 955 through the full gamut of our CPU test suite. We will add its distinctiveness to our own.