Conclusions
The Pentium 4 670 is, I think, a good example of why the single-core approach wasn't working so well for Intel. Despite its high clock speed, the P4 670 struggles in some single-threaded applications, particularly games. The comparably priced Athlon 64 FX-55 is much faster, and so is the much cheaper Athlon 64 3500+. Multithreaded apps do take advantage of Hyper-Threading and make the P4 670 more competitive—perhaps on par with the Athlon 64 FX-55 overall when multiple threads are in use. Even so, a Pentium 4 670-based system consumes about 45 more watts under load than an FX-55 system. Intel has managed to tame the Prescott core's heat and power needs somewhat through power management schemes and better manufacturing, but it's still rather hungry when going full tilt.

The Pentium D 820 typifies Intel's new approach, which looks very appealing given the numbers we've seen here today. In multithreaded applications, the Pentium D 820 races by the Athlon 64 3500+, which is a more expensive CPU. In fact, the Pentium D 820 frequently outperforms the Athlon 64 FX-55 and the Pentium 4 670, and our Pentium D system consumes no more power under load than our Pentium 4 670 rig.

Still, Pentium D 820's performance does present some rather bold contrasts. It's the slowest CPU in the pack whenever we throw a single-threaded test at it. The 820's gaming performance especially raises some red flags for us, as we've noted. Eventually, games will most likely make the conversion to multithreading, but in the interim, I worry that the newest, most intensive game engines may not run terribly well on a Pentium D at 2.8GHz. Many games will work just fine, no doubt, but those that use lots of AI or physics may be a strain. Hard-core gamers will want to stay away, as will others who extensively use one single-threaded application at a time. The Athlon 64 3500+ is the better choice for them.

With that caveat noted, the Pentium D 820 is still a hellvua bargain at $241, and it's not even the true sweet spot for the Pentium D line. I'd probably pay the $60 or so premium for the extra 200MHz per core offered by the Pentium D 830, personally, just to be sure that my single-threaded performance was snappy enough to satisfy.

I expect the Pentium D processor, teamed up with the 945G chipset, to dominate the mid-range PC market once folks discover its virtues. For everything from corporate desktops to boxes for power users, from video editing workstations to home theater PCs, the Pentium D looks tough to beat. (AMD's Athlon 64 X2 is an amazing CPU, but with prices starting at over $500, it will be a high-end choice only.) Even casual gamers will want to take a long, hard look at the Pentium D. It fuses the creamy smoothness of true symmetric multiprocessing with the simplicity and affordability of commodity desktop PC components—a combo that's awfully hard not to like. What's more, the Pentium D, P4 670, and the 945 chipset should all be available starting today, according to Intel. Make mine twins, please.