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With a winch in front and a spare tire hanging off the back
Just in case we didn't entirely feel the vibe of the Quad FX concept, AMD decided to send out an entire system for review, and it's a "4x4" through and through—the Hummer H2 of enthusiast boxen, a veritable hymn to conspicuous consumption in PC form, complete with knobby tires and ample ground clearance. Don't take it from me, though. Have a look at this beast.




This box's vitals include two FX-74 processors, an Asus L1N64-SLI WS mobo, 4GB of memory in the form of Corsair Dominator DIMMs, a pair of WD 150GB Raptors in RAID 0, a 500GB drive for additional storage, a 1kW PSU, and a couple of GeForce 7900 GTX cards in SLI. The chassis is a Thermaltake enclosure with a new door panel that has dual ports above the CPU coolers and internal tunnels that extend down to meet the top of those coolers. (AMD says production versions of this enclosure should be available soon.)

Of course, our first task, after photography, was to disassemble this system and set up the CPU and processors in our standard configuration for testing. But I did let the system run long enough to note that it doesn't actually sound "like an Oreck XL on Metabolife," as I had feared. This isn't the quietest box by any means, but its cooling design makes it sound fairly reasonable, believe it or not.

Incidentally, when I first tried to set up the core of the Quad FX system on the test bench using our standard OCZ GameXStream 700W power supply, the system wouldn't POST properly. After trying a number of things without success, including cutting back to a Radeon X300 video card, I was able to get the system working by swapping in a BFG Tech 1000W PSU. Later, I tried subbing in an OCZ PowerStream 520W PSU, and the system would POST fine with it. I'm not sure whether its reluctance to POST with the GameXStream was just an odd incompatibility or a sign of something larger, but you will definitely need a good power supply unit to feed a Quad FX system, regardless. We'll talk more about power use shortly.

Putting four cores to proper use
The process of putting together our review of Intel's first quad-core processor made clear to us the difficulty of taking full advantage of four CPU cores. Many of the apps in our usual CPU test suite are multithreaded, but only a handful of them use more than two cores effectively. Even in applications like video encoding, where the problem would seem to be imminently parallelizable, many programs don't spin off more than two threads because, historically, four-way systems have been extremely rare in nearly every province of computing except for high-end servers.

Of course, that means that on one level, stepping a quad-core system through a series of desktop-class apps and showing little or no performance gain compared to dual-core systems, as we did in our QX6700 review, is an entirely valid exercise. It is not, however, especially satisfying, because it doesn't address the larger questions of a quad-core system's potential, either in terms of performance with widely multithreaded apps or of scaling from two cores to four. We decided to attempt to address these questions with this article, so we have sought out applications that can use more than two threads and focused on them. As a result, the following set of tests is a little bit unusual; the applications are less common and a little more academic in nature. Indulge us, if you will, as we attempt to learn what performance gains quad-core systems can bring. Keep in mind, though, that going from two cores to four won't necessarily bring these sorts of performance improvements across the board. A look at our QX6700 review should dispel that notion.