Conclusions
Well, jeez, it's hard not to like the Phenom II X3 720, which is just a bundle of gimpy goodness. Thanks to its higher clock speed and larger cache, the X3 720 quite frequently outperforms its bigger brother, the Phenom II X4 810, even though it costs less. And, at 2.8GHz, the 720 is fast enough to match up pretty well against the Core 2 Duo E8400 in many applications—including games—that tend to run best with fewer and faster cores. In more widely multithreaded apps where the 720's third core kicks in, the Phenom II X3 almost always outruns the E8400, sometimes dramatically. Oddly enough, the 720's combination of three cores and relatively high clock speeds may be the ideal trade-off for the current state of PC software. Who knew?

Add in the X3 720's fairly tame power consumption, its apparently excellent overclocking proposition, and the fact that—regardless of memory type—the Phenom II has a superior system architecture to the Core 2, and the E8400 starts to look rather weak by comparison. The Phenom II X3 720 is our new favorite among mid-range PC processors. Look for it to secure a place in one of the builds in our upcoming system guide refresh.

The Phenom II X4 810 is also generally faster and more attractive overall than the Core 2 Quad Q8200, but I can't say I like the value propsition with either of these processors all that well. Because of their reduced cache sizes and clock speeds, these value quad-cores rely almost entirely on multithreaded applications to achieve strong performance. When software doesn't oblige (and it often doesn't), they stumble, as illustrated by the Q8200's poor showings in several of our benchmarks, including MS Office, Firefox, and the gaming tests. For the vast majority of users, the Phenom II X3 720 will be a better choice, and it costs less.

Oh, and we didn't see much in the way of performance gains when moving the Phenom II X4 810 from DDR2 memory to DDR3 memory. That's no great shock, all things considered, and no knock on AMD's implementation of Socket AM3. I suspect we may see more benefits from DDR3 once we get our hands on a non-neutered Socket AM3 quad-core, like a Phenom II X4 940 or something even faster, especially if AMD builds in support for higher memory frequencies. Until then, Socket AM3 is a fine upgrade path waiting for a reason to exist.