The processor uses a 7x multiplier matched to a 133MHz FSB (Front Side Bus) to reach 933MHz. The 133MHz FSB has two advantages over the older 100MHz FSB. First, the extra 33MHz gives the processor an additional 33% bandwidth boost. Second, the faster FSB allows higher clock speeds with lower multipliers. You probably won't see Slot1 Pentium III processors using a 100MHz FSB running above 850MHz.

Because we have gone through it so many times before, we will spare you the in-depth discussion of the Coppermine architecture and just give you the highlights.

Like its Coppermine siblings, the Pentium III 933MHz owes much of its performance to 256K of on-die "Advanced Transfer Cache." Running at full processor speed and connected via a 256-bit wide data path, the cache keeps the P6 CPU core of the Pentium III well fed, even at speeds of 933MHz and beyond. The full-speed L2 cache allows the Pentium III to scale well, without a major drop-off in performance as clock speed rises.

The older version Pentium III design carried 512K of "Discrete" cache running at half the processor speed with less efficient transfer methods. If Intel kept with the old style cache, the 933MHz performance would likely be significantly lower than it is today.

As evidence of the perils of a slower cache, the AMD Athlon is currently facing significant performance drop-offs at higher clock speeds. The Pentium III 866MHz outperforms even the 1GHz Athlon in some tests. Later in this article, you will be able to see how the various speeds of Athlon and Pentium III compare. On the positive side, AMD is rectifying their L2 cache speed limitation in the next generation of their Athlon, code-named Thunderbird.

You can read more details of the ATC system in our Intel Pentium III 500E and 550E FC-PGA CPU Review.