Viperslair has posted a review on the AMD Athlon XP 1800+ (1.53GHz)

Perhaps the most controversial aspect of the XP is the return of the performance rating. Collaborating with Cyrix about 5 years ago, the two manufacturers lagged a little behind Intel in clock frequencies. The consumer back then, and this thinking hasn't really changed much today, would likely conclude that a higher clocked processor is faster, regardless of manufacturer. This PR system was introduced to make their own processors appear to be similar to Intel in terms of performance.

Now, unlike the past, where the PR was a rating compared to an Intel CPU, this is not the case now. It's a common misconception, but the PR rating does not compare an Athlon XP against a Pentium 4, but against a Thunderbird. Therefore, a 1.53GHz XP performs like an 1.8GHz Thunderbird. How did they come up with these numbers? Testing, and a lot of it.

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