A five-way refresh from AMD

Not long after the debut of the Clarkdale lineup, AMD conducted a freshening up of nearly its entire desktop CPU range. This move was unusual in a couple of ways: because it involved the introduction of five new CPU models at once, and because each one of them represents only a 100MHz clock speed increase over the prior incumbent at the same price point. The update was broad but incremental, serving as a bit of a price cut and a minor performance boost.

Top row: Athlon II X2 255, Athlon II X3 440, Athlon II X4 635.
Bottom row: Phenom II X2 555, Phenom II X4 910e.

The case is not without some singular features, though, as Sherlock Holmes would say. In fact, this calls for us to bust out our table of the current processor types, like so:

Code name	Key products	Cores	Threads	Last-level cache size	Process node (Nanometers)	Estimated transistors (Millions)	Die area (mm²)
Penryn	Core 2 Duo	2	2	6 MB	45	410	107
Bloomfield	Core i7	4	8	8 MB	45	731	263
Lynnfield	Core i5, i7	4	8	8 MB	45	774	296
Westmere	Core i3, i5	2	4	4 MB	32	383	81
Deneb	Phenom II	4	4	6 MB	45	758	258
Propus/Rana	Athlon II X4/X3	4	4	512 KB x 4	45	300	169
Regor	Athlon II X2	2	2	1 MB x 2	45	234	118

Athlon II X2 processors are based on the chip code-named Regor, a relative newcomer to AMD's lineup. Regor features two Phenom II-class processor cores, each with 1MB of L2 cache. Like other Athlon IIs, it has no L3 cache. Regor may not impress the ladies with its neck-snapping acceleration, but it's a relatively small chip that ought to draw power rather modestly and be cheap to produce. The Athlon II X2 255, for instance, has a healthy 3.1GHz clock speed, a 65W TDP, and a price tag of just 74 bucks—not a bad combo, all things considered.
We've picked up another code name in our table along the way, too: "Rana," used to denote Athlon II X3 chips based on the Propus silicon that powers the value quad-core Athlon II X4 chips. Why we need another code name for the same silicon with a core disabled is beyond me, but I think the answer has to do with the fact that additional code names cost nothing. And marketing people need something to do with their time. The logic seems to be: "Yeah, I used to be called Bart, before I lost my leg in 'nam and changed my name to Dexter."
Regardless of the code-name chicanery, AMD's value-oriented quad- and triple-core parts are a pretty savvy response to the excellent Core i3. AMD can't offer you Clarkdale-class computing power in two cores, but they can give you more cores at the same price—at the cost of some additional power consumption and heat production. The first five lines of the table below detail the new models AMD recently introduced.

Model	Cores	Base core clock speed	Last-level cache size	Black Edition?	TDP	Price
Athlon II X2 255	2	3.1GHz	2 x 1 MB L2	-	65W	$74
Athlon II X3 440	3	3.0GHz	3 x 512 KB L2	-	95W	$84
Athlon II X4 635	4	2.9GHz	4 x 512 KB L2	-	95W	$119
Phenom II X2 555	2	3.2GHz	6 MB L3	Y	80W	$99
Phenom II X4 910e	4	2.6GHz	6 MB L3	-	65W	$169
Phenom II X4 965	4	3.4GHz	6 MB L3	Y	125W	$195

We've tested four of the five new parts, including all of the Athlon II chips. The Phenom II X4 910e is a low-power version of the Phenom II with a 65W TDP. We haven't had time to run it through our full benchmark suite, but we have measured its power efficiency.
The one new model we've neglected, simply due to lack of time, is the Phenom II X2 555, a dual-core variant of the Phenom II that's also a Black Edition chip with an unlocked multiplier. We happen to think the Athlon II X3 and X4 processors are potentially more compelling, but if you want to get a feel for how the X2 555 might perform, we have a full set of results for its younger sibling, the X2 550. If you squint hard enough when reading our graphs, you won't be able to see the effect the extra 100MHz might have in the X2 555, anyhow.
I've included the Phenom II X4 965 in the table above because it represents the absolute top end of AMD's desktop CPU line—at only $195. AMD can't really ask any more than that given Intel's current performance dominance, and the situation has led to a very compressed product stack. AMD does offer a host of Athlon II and Phenom II processors at varying price points and clock frequencies, but the differences between them are fairly small. One thing you won't find in the new lineup: a Phenom II X3 processor. The triple-core options now appear to be confined to the Athlon II line, which probably makes sense under the circumstances.
Kicking it old school with LGA775
In response to CPU round-ups like this one, we often get requests for the inclusion of older processors, so folks can have a better sense of how an upgrade might serve them. Happily, this time around, we were able to test a couple of older processors as points of reference.
The newer of the two is the Core 2 Quad Q6600, which debuted just over three years ago at a very healthy price of $851. A 2.4GHz quad-core part based on 65-nm Conroe/Kentsfield silicon, the Q6600 became an enduring enthusiast favorite as its price dropped over time. I expect these CPUs are still at work in the systems of quite a few TR readers to this day. What's more, the Q6600's showing in single- and dual-threaded applications should essentially match that of the Core 2 Duo E6600, another popular pick from the same period.
If that's not old school enough for you, how about some Prescott action? The Pentium 4 670 is a single-core, 90-nanometer CPU clocked at a heady 3.8GHz. The P4 670 first hit the market nearly five years ago and was among the fastest desktop processors Intel offered at the time. Of course, that was a rather dark time for Intel, because AMD had an iron grip on the performance lead—especially in games. Still, the P4 670 was essentially state of the art, with reasonably competitive performance overall. In fact, it's pretty much as far back as we can reach in Intel's product stable while maintaining compatibility with our 64-bit operating system and applications. The applications in today's benchmark suite are much more broadly multithreaded, too, which could allow the P4 to take better advantage of its Hyper-Threading capability than it could back in the day.
Then again, I wouldn't get too worked up about the prospects for a dual-threaded, 3.8GHz CPU from five years ago if I were you.
We've used older Intel processors for comparison not to rub Intel's nose in a troubled period from its past, but because of the incredible track record of socket compatibility the firm has amassed during LGA775's run. Older motherboards weren't always capable of supporting newer CPUs, but we were able to drop both the Q6600 and the P4 670 in our new Asus G43 motherboard, boot up, and go to town. That enabled us to include these CPUs without the need to equip an additional test system.
Key contests to watch
Since we've tested such a broad range of processors, let me point out a few match-ups between Intel and AMD that are worth watching. The main one, of course, is our headliner, the contest between the Core i3-530 at $113 and the Athlon II X4 635 at $119. You know the outlines of that one. Pay careful attention to the contrasts in performance, power draw, and overclocking potential between these two processors, because I have a feeling this could be a close one, all told.
We don't often test CPUs as cheap as the Athlon II X2 255, which rings up at just 74 bucks. But we have this time, and we've also tested its direct rival from Intel at the same price, the Pentium E6500. The E6500 is based on an older Penryn (Core 2 Duo) chip running at 2.93GHz on a 1066MHz bus with just 2MB of L2 cache. Those specs ought to put it very close to the X2 255, which ticks away at 3.1GHz and has a total of 2MB of L2 cache, as well. Penryn's per-clock performance has generally been a little better than recent AMD processors, so the outcome is in no way assured. Both processors share the same 65W TDP rating.
I wish we had a Pentium G6950 to compare to the Athlon II X3 440, because those two chips are direct competitors. Perhaps we can snag one for testing next time around, but we at least have full results for the X3 440 now.