Conclusions
The Phenom quite obviously isn't a bad CPU design, given the way it performs on a per-clock basis and how its performance scales from one to four threads. In many cases, its enhanced execution cores crank out some solid gains in instructions per clock over AMD's Athlon 64 X2. Also, the addition of two more cores can bring substantial performance increases in applications able to take advantage of them, as many of our tests have shown. But at the end of the day, CPU performance comes down to a couple of variables, performance per clock and clock speed, and the Phenom doesn't have enough of either to allow it to catch up with Intel's fastest 65nm Core 2 processors, let alone the even-more-potent 45nm ones. I sound like a broken record, but AMD is going to have to achieve something close to clock speed parity with Intel in order to compete for the overall performance lead. That's how closely these two architectures appear to be matched at this point.

The Phenom 9900 does show some promise at 2.6GHz, but it may not be available until—who knows?—perhaps Februrary or March. Until then, the Phenom 9600 will do battle at 2.3GHz against Intel's Core 2 Quad Q6600 and its presumptive 45nm successor. AMD has priced the 9600 to compete with the Q6600, and that makes it a potentially attractive product. However, the Phenom's well-publicized clock frequency issues keep it from being a slam-dunk. The Phenom 9600 was generally a little slower overall in our tests than the Q6600. If it ran at 2.4GHz, then it might be comparatively stronger. AMD's plan to release an unlocked version of the Phenom 9600 may help tip the scales in the 9600's favor for some folks, but I suspect they won't find much overclocking headroom in those chips. In fact, our 2.6GHz engineering sample wasn't 100% stable, which is why you won't find any overclocking results in this review.

Unlike in the server space, where Intel's use of FB-DIMMs gives AMD a built-in advantage, the Phenom trails Intel's 65nm processors in power efficiency and really doesn't come close to Intel's 45nm models. The picture would look better here, at least at idle and during periods of intermediate use, had our test system been stable with Cool'n'Quiet clock throttling enabled. This is, after all, one of the big advantages of the Phenom's native quad-core design. But it has to work properly in order to be an advantage, and at the time of the product's public release, we don't yet have an example that does. As you may have gathered from the preceding pages full of test results, we're not ones to take things on faith from hardware makers—for good reason.

One bright spot here is the upgrade proposition the Phenom offers to current owners of Socket AM2-based systems. Those folks now have an affordable path to a quad-core solution that's nearly as fast as a Core 2 Quad Q6600, which is a fine thing and a no-brainer upgrade choice. That said, Socket AM2 owners will want to watch the fine print carefully. Obviously, you won't get the power savings of split power planes or the increased data rate of HyperTransport 3.0 if you drop a Phenom into an older motherboard. Also, I haven't yet had time to confirm this myself in a test rig, but I believe the Phenom's north bridge clock will run a little slower on Socket AM2 board, leading to somewhat reduced performance.

The immediate path ahead for AMD is blindingly obvious. They're going to have to supply enough Phenom 9500 and 9600 chips to meet demand, which could be a challenge, and they're going to have to work on reaching higher clock frequencies as soon as they can. They also have some work to do, along with their partners, in bringing the Phenom's Socket AM2+ infrastructure up to snuff. The chipset operation AMD purchased in the ATI acquisition was in many ways still a fledgling effort, and our initial experiences with 790FX motherboards haven't inspired much confidence. AMD has convinced Asus, Gigabyte, and MSI to produce 790FX-based boards, but it doesn't appear to have convinced them to dedicate top-shelf engineering resources to these efforts. We will, of course, be working to get our hands on newer versions of Phenom and 790FX hardware as these products become available consumers. We're hopeful that our experiences with the final products will be better than what we've seen to date.