Conclusions
Our benchmarks have dramatically illustrated the power of thread-level parallelism to enhance performance. The Pentium Extreme Edition 840 was able to take advantage of this effect to outshine its primary single-core competitors, the Athlon 64 FX-55 and P4 Extreme Edition 3.73GHz, in a range of multithreaded applications. Even without considering its multitasking benefits, the Pentium XE 840 looks like a worthy addition to Intel's Extreme Edition lineup, so long as threading is the name of the game. Throw in the smoother multitasking that comes with any SMP system, and the logic behind the XE 840 begins to make sense.

Unfortunately, not all applications are multithreaded, and many won't be for months or even years into the future. The relatively slow 3.2GHz clock speed of the XE 840 demands a real shift in mindset in order to accept the loss of single-threaded performance in exchange for multicore bliss. I wouldn't expect big-time PC gamers, some of the Extreme Edition line's supposed target customers, to accept this tradeoff willingly. Gamers would be better served by the P4 Extreme Edition 3.73GHz, or, as we have pointed out in the past, practically any variety of Athlon 64 down to the 3500+. Non-gamers who use mainly single-threaded applications may not want to accept the XE 840's slower performance, either.

Probably the most direct competitor for the Pentium Extreme Edition 840, in terms of pricing and technology, is AMD's Opteron 175, which is also a dual-core chip and also priced at a princely $999. Compared to the Opteron 175, the Extreme Edition 840 is generally somewhat slower overall in multithreaded applications and much slower overall in single-threaded applications. Not only that, but a system based on the Extreme Edition 840 is extreme in another sense: it consumes over 100W more power under load than an Opteron 175-based system. All told, that's a rough combination of elements for the Extreme Edition 840. The competition is not making things easy. Perhaps the XE 840's saving grace will be the relative obscurity of the Opteron 100 series, should AMD continue that odd tradition. However, since neither the Extreme Edition 840 nor the Opteron 175 is generally available for purchase today, I hate to speculate on how the availability picture will shake out.

Taking the long view, Intel seems to have a sound strategy for dual-core processors overall. Although this thousand-dollar wonder is a little bit inaccessible for most folks, the Pentium D 840 looks promising, and the cheaper versions look even more exciting. If Intel follows through with Smithfield chips for under $300, as I expect it will, then the Pentium D will be doing battle in earnest for the hearts and wallets of an awful lot of real PC enthusiasts, who will be asking some very hard questions about the merits of exchanging better gaming performance for better video encoding and creamy smooth multitasking. I'm curious to see what answers they choose.