AMD Athlon 800

by Anand Lal Shimpi on December 20, 1999 4:47 AM EST
We all make mistakes, and on October 4, 1999, in our review of the AMD Athlon 700, we implied that the last Athlon released this year would be the 700MHz part. Shortly thereafter, Intel released a 733MHz Pentium III which forced Compaq to pressure AMD into releasing an Athlon with a higher clock speed and, thus, the Athlon 750 was announced on the 29th of November.

As if that were not excessive enough, with rumors that Intel was going to start sampling their Pentium III based on the new Coppermine core in 750MHz and 800MHz flavors, AMD was pressured to release data on their competing product early. And thus we have our review of the AMD Athlon 800.

The Athlon 800, in brief, is just a faster version of the Athlon 750. It is based on the same 0.18-micron K75 core as the 750, and features a 2/5 L2 cache divider (or 0.4x L2 cache multiplier if you hate fractions) thus giving it a slower L2 cache than the Athlon 700 which was the last Athlon to run its L2 cache at 1/2 the core clock speed.

AMD is currently in a very interesting situation -- they have the ability to push the clock speed of the Athlon to even higher levels; the air-cooled 1GHz mark isn't too far away. If you recall, just four months ago, the only way to get an 800MHz Athlon was through Kryotech's Cool Athlon 800 that ran the CPU at -36 C and, now, we are able to achieve the same results via air cooling alone. So what is AMD's problem?

As we mentioned in our review of the Athlon 750, the problem AMD is running into is getting fast enough L2 cache chips to keep up with the increasing clock speed of the processors because they are dependent on third party manufacturers to produce the L2 cache chips for the processors. The only true solution for this problem is to move the L2 cache off of the Slot-A processor card and onto the die of the Athlon; unfortunately, this move is not scheduled to happen until sometime in the first half of 2000. While that isn't very far away, AMD can't remain idle and let Intel win the clock speed battle; clock speed sells more processors than technology.

While it is hard for all of us to believe, in the end, when you have someone that hasn't the slightest clue about what an L2 cache is and why a faster one is a good thing, the only "performance" data that they can base their buying decision on is clock speed, and the "higher is better" theory comes into play here. This is why a big retail vendor like Compaq, would push for the release of an Athlon with a higher clock speed.

If they continue down this road, eventually the performance difference between the Athlon, with its cache increasing at rates now less than ½ of the increase in clock speed, and the Pentium III, with its cache increasing directly with the clock speed, will grow to such a point that the Athlon will clearly be the slower processor.

Luckily, AMD's roadmap does not place the Athlon on that path for too long as they will soon move the L2 cache onto the Athlon's die with their Thunderbird and Spitfire cores. The problem here is that, while they are competing with Intel on a clock for clock basis, they are going to start losing the performance battle in certain situations. While professional applications that can enjoy the Athlon's superior FPU will continue to perform at a superior level on the Athlon, business, productivity and even some games may begin to favor the Pentium III over the Athlon due to the Pentium III's L2 cache speed advantage.

The Athlon on the losing side?

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