We couldn’t leave out the problem of overclocking in this review. Many users buy value processors to use them at higher frequencies than rated by the manufacturer. Cheap processors often have a nice overclockability, so owners of such products may squeeze them out for a higher (and sometimes much higher) performance. So we decided to add an overclocking-related section into this roundup.
Intel Celeron. The above-described Celeron processors feature good overclockability. Their overclocking potential largely depends on the tech process employed in their production. Particularly, models with 1.7 and 1.8GHz clock rates are produced with the 0.18-micron process and are bad at overclocking: the old manufacturing technology doesn’t allow for a good speedup. After increasing the Vcore by 10-15% and without applying any special cooling methods, you can usually raise the frequency of such a processor to 2.0-2.1GHz. Thus, junior Celeron models don’t suit for overclocking.
Models whose frequency starts from 2GHz are produced using the advanced 0.13 tech process. This fact explains their good overclockability, to 3.0GHz and higher. Newer Celerons are a little better at overclocking than older ones, but older Celerons with lower frequencies may provide higher performance as they support faster FSB clock rates, and the FSB frequency is among the basic bottlenecks in Celeron-based systems.
Intel Pentium 4 1.8A. This CPU is one of the overclocker’s favorites. The Pentium 4 1.8A is among the junior Pentium 4 models on the 0.13-micron Northwood core and it can easily speed up reaching the frequencies of top-end Pentium 4 on this core. Nearly all Pentium 4 1.8A chips can overcome the 3GHz barrier and many such processors are stable at 3.2GHz and higher. You overclock the Pentium 4 1.8A through increasing the FSB because this CPU, like the Celeron, has a locked multiplier.
AMD Athlon XP. As I said above, Athlon XP processors are based on two cores: Thoroughbred and Barton (Thorton). Anyway, notwithstanding the different amount of cache memory in these cores, they are both produced with the same 0.13-micron tech process. As a result, all CPUs of this family have similar overclockability. Thus, Thoroughbred-core processors usually speed up to 2.1-2.2GHz after you increase the Vcore by 10-15%. Processors on the Barton and Thorton cores can reach higher, to 2.2-2.3GHz. All latest models of the Athlon XP have a locked multiplier and you overclock them by increasing the FSB clock rate, like with the Celeron and Pentium 4. Well, FSB overclocking provides additional performance gains.
Now that AMD and Intel have both focused on producing newer and advanced CPU series, the processor cores employed in the value sector have been unchanged for long. This makes me think that the above-mentioned overclocking limits will remain such in the future. That’s why we decided to overclock and compare the performance of the Celeron, Athlon XP and Pentium 4 1.8A, which fits into the definition of a value processor. I didn’t want to test numerous analogous CPUs differing in the regular frequency only, so I just took the junior members from each family. These processors are overclocked like the top-end models, but provide a higher performance due to the higher FSB clock rate that contributes to the overall system speed. Moreover, people who buy a processor with overclocking in mind are likely to prefer models with lesser clock rates and prices, but that would show the same performance as top-end models. I overclocked all processors by increasing the FSB frequency and without changing the multiplier (well, I couldn’t – it is locked in all modern value processors).