Perhaps it was the competition. Intel's Pentium 4 Extreme Edition was magically transmogrified from a Xeon into a desktop part to do battle with the Athlon 64 FX, and Intel recently cranked the P4 Extreme Edition up to 3.4GHz. The Overall Performance Lead is a very important thing to have, especially if you're playing number two to an 800-pound gorilla like Intel. Or perhaps it was just time for AMD's Hammer processors to make the move to 2.4GHz, finally reaching clock speeds higher than their Athlon XP predecessors.

Whatever the case, the Athlon 64 FX-53 is here, ready to challenge the P4 Extreme Edition and all comers for the Overall Performance Lead in the x86 processor world. To gauge the FX-53's success in its quest for the Overall Performance Lead, we've lined up sixteen of its competitors and tested it against 'em all. Our contestants range from the exotic (the P4 Extreme Edition 3.4GHz) to the novel (the Pentium 4 Prescott) to the massively overclocked (the Athlon XP-M 2500+ dialed up to 2.4GHz.) To make things even more interesting, we'll be exploring how the various AMD and Intel processors assembled here scale with clock speed and model number increases.

I promise, if you like performance graphs like I do, this review will satisfy your cravings. Read on to see what I mean.

Big picture of the chip
Here, folks, is a big picture of the chip.

To review, the Athlon 64 FX is much like AMD's regular Athlon 64 processors. Like the Athlon 64, it has a 1MB L2 cache on chip and a built-in memory controller with support for DDR400 memory. Like the Athlon 64, it has support for SSE2 and extensions for 64-bit memory addressing, giving it a healthy dose of future-proofing. Unlike the Athlon 64, though, the Athlon 64 FX nestles into a 940-pin socket and supports dual channels of DDR400 memory, giving it up to 6.4GB/s of memory bandwidth.

To unlock this goodness, you'll need a 940-pin motherboard and registered DIMMs, because the Athlon 64 FX won't work with regular ol' unbuffered memory. AMD has said that all Athlon 64 chips, including the FX line, will eventually be moved to a new 939-pin socket that doesn't require registered DIMMs. However, that glorious day hasn't come yet. For our testing, we used an Asus SK8N motherboard and a pair of Corsair CMX512RE-3200LL memory modules.

About the funny line graphs
Many of the graphs you'll find on the following pages are colored line graphs intended to demonstrate how the various processor types we've tested scale with clock speed increases and other such enhancements. We've used such graphs before in processor and graphics reviews, but they're a little tricky here. In this case, we have six distinct CPU types, ranging from the Athlon XP to the new Pentium 4 "Prescott" processors, and we have multiple performance grades of each type. The Pentium 4 chips are plotted according to straight clock speeds. For the AMD chips, we've graphed them according to their model numbers, provided they correspond roughly to Pentium 4 clock speeds.

That leaves a couple of exceptions. Most prominently, we have today's star, the Athlon 64 FX-53. I chose to graph the Athlon 64 FX chips to correspond with the clock speeds of the regular, non-FX Athlon 64 processors. As a result, the Athlon 64 FX-53 is in a category that's currently all its own. I believe this arrangement makes sense, all things considered. Then there's the Athlon XP-M 2500+, which we have overclocked to 2.4GHz. Since the Athlon XP 3200+ runs at 2.2GHz, the XP-M at 2.4GHz was the next logical step in the sequence, so I've plotted it as a "3400." Once we get to the line graphs, you'll see what I mean. Again, I think this placement is eminently sensible. You'll see for yourself shortly.

Finally, we've used the Pentium 4's "C" and "E" designations on our bar graphs, where we can list individual product names one by one, while we've stuck with codenames on the line graphs, where a single letter designation would be inadequate to capture the lovely nuances of Intel's product naming schemes. If all this talk of Northwoods and Prescotts baffles you, please read our Pentium 4 Prescott review to become further confused.