Yes, I know, the title is sensational. There's really nothing to get excited about.

While it might look great at first glance, gaining unofficial DDR400 support for Athlon XP-based systems is hardly anything too special. There are some perfectly good reasons why DDR400 is essentially useless for Athlon XP systems.

The first reason is simple; the Athlon's FSB allows no more than a peak bandwidth of 2.1GB/s (this 2.1GB/s of bandwidth is achieved through the Athlon's double pumped 266MHz FSB). Knowing that DDR400 memory (also know as PC3200) has a peak theoretical bandwidth of ~ 3.2 GB/s, you can see that a lot of that bandwidth is simply unnecessary. Even DDR333 (PC2700) memory, which offers a peak bandwidth of 2.7GB/s, essentially adds, at best, a few percentage points to application performance compared to previous DDR266 (PC2100)-powered Athlon XP platforms.

Probably the most famous example of useless additional bandwidth is NVIDIA's nForce chipset, launched at Computex in June of 2001. Nearly every computer hardware website on the Internet was hyped about NVIDIA's nForce, which was supposed to offer all sorts of revolutionary features, one of which was coined "TwinBank." TwinBank was just another name for dual channel memory, a technology first introduced in Intel's 840 Rambus chipset. With nForce supporting dual channel DDR266 memory, an enormous 4.2GB/s of bandwidth was available for consumption, instead of the "meager" 2.1GB/s of bandwidth the other competing solutions were providing. But when the hardware community finally got its hands on nForce boards for testing, it became clear that nForce was more evolutionary than revolutionary, offering performance about on par with other solutions like VIA's KT266A. At that point it was clear; if Athlon processors continued to have no higher than a peak bandwidth of 2.1GB/s available via the Athlon's FSB, any more bandwidth would just be worthless (unless it were to feed a graphics core of course, which is exactly what nForce ended up doing).

Another reason you can expect DDR400 to offer little value to Athlon XP systems is the simple fact that DDR400 is an unapproved specification. The Joint Electron Device Engineering Council (JEDEC) has yet to approve a DDR400 specification, and this in turn makes it difficult for chipset makers, memory makers, and other related companies to create reliable products based around DDR400.

So not only is DDR400 an unapproved specification, but the Athlon's FSB can't take advantage of the 3.2GB/s of DDR400 anyway, even IF DDR400 were a specification at this point.

OK, you must be thinking "Then what's so special about today's review if DDR400 doesn't matter?" Well, that's a very interesting question, how about you read on to find out. :)

KT400 Up Close
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  • SoSolid - Saturday, July 26, 2003 - link

    Today I discoverd that the fifth PCI slot of my Gigabyte GA-7VTXE+ was malfuntioning. As a Gigabyte fan my first thought was to buy a new Gigabyte mothterboard.
    However I recall it was much more expensive than the upcoming 333MHz boards. So I decided to look around for an other board. Today I heared about the Asus A7V8X-X. After reading various information and this review I believe buying the A7V8X(-X) will be the right choice.

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