Intel's 15 Most Unforgettable x86 CPUs

The Pentium 4: A Lot Of Noise Over Very Little

In November 2000, Intel announced its new processor, the Pentium 4. With a higher clock speed (at least 1,400 MHz), this processor had a major drawback in that its performance wasn’t as good as competing models on a per-clock basis. AMD’s Athlon (and even the Pentium III) performed better at the same frequency. Complicating matters, Intel tried to shift to Rambus’ RDRAM memory (the only memory at the time capable of meeting the requirements of the CPU’s FSB), but failed. Expensive and hot, the Pentium 4 nonetheless managed, with many modifications, to more or less stay in the competition for a few years (by adding L3 cache and technologies like Hyper-Threading).

Mobile versions (with a variable multiplier), Celeron versions (with a smaller L2 cache), and Xeon versions (with an L3 cache) of the Pentium 4 were sold. Hyper-Threading and the L3 cache are two technologies that first appeared on servers and were then adapted to standard processors (though L3 cache was available only on the expensive EE models).

We should also mention the FSB, which was clocked at a fourth of the nominal clock frequency, using what is called Quad Data Rate (QDR) technology—a 400 MHz bus is actually 100 MHz QDR, 533 MHz is 133 MHz QDR, etc. Finally, 64-bit versions of the Pentium 4 appeared in 2005, which we’ll talk about later on.