Conclusions
The fact that Intel retains the overall performance crown comes as no surprise. As we said at the outset, AMD has no real answer to the Core 2 Extreme X6800 among its dual-core processors. Also, Intel's quad-core CPUs tend to scale better than AMD's Quad FX platform, especially for typical desktop-class applications. Our move to Windows Vista x64 has done little to alter this dynamic. At the same time, Core 2 processors tend to draw less power and to be more energy efficient—sometimes markedly so—than Athlon 64s. Right now, Intel has the magic combination of a superior processor microarchitecture and a more mature, fully realized 65nm manufacturing capability working together on its side.

This one-two punch has allowed Intel to maintain a performance edge at most price points, despite standing pat through AMD's aggressive pricing moves and new model introductions. AMD's current weaknesses manifest themselves most fully in its high-end models, like the Athlon 64 X2 6000+, which draws more power at peak than the Core 2 Extreme QX6700 yet is often outperformed by the less expensive Core 2 Duo E6600. The Athlon 64 looks more competitive in its lower-end incarnations like the X2 5000+ and 4400+, which match up better on both performance and power characteristics against the Core 2 Duo E6300 and E6400. These processors have the benefit of being available in 65nm form, and I'd say the minor performance penalty one pays in performance at 65nm (due to the slower L2 cache) is worth it for the reduced power draw.

This low-to-mid-range territory, incidentally, is where I'd be looking to buy. Many of our tests have shown the benefits of quad-core processors, but honestly, finding applications that will make good use of four cores is not easy—and the list of games that really use four cores is approximately zero. I'd probably grab a Core 2 Duo E6400 and overclock it until it started to glow, if I were putting together a system right now. I must admit, though, that I have an almost irrational fondness for the Core 2 Quad Q6600, probably because it's the most energy efficient processor in our Cinebench power test. The thing is by no means a great deal—two E6600s will set you back over $200 less than a single Q6600—but it's easy to imagine a near-silent multitasking monster built around one.

AMD would do well to expand its 65nm offerings into higher clock frequencies as soon as it can reasonably do so. That may take a while yet, given the limited overclocking headroom we've seen from early 65nm Athlon 64 X2s. Meanwhile, Intel isn't likely to sit still for much longer. Rumors of an April price cut abound, and in light of the Core 2's ample frequency headroom, higher speed grades are a definite possibility, as well. For AMD, its next-generation microarchitecture can't come a moment too soon.