Business Benchmarks

Winbench 99
CPU speed	CPUMark32	Business Diskmark99
Pentium III 620	1560	Crashed
Pentium III 560	1400	2840
Pentium III 500	1250	2820
Celeron 550A	1240	N/A
Pentium II 500	1180	2680
Pentium II 450	1120	2390
Pentium II 400	1000	2350
Celeron 333	832	N/A

The Pentium III overclocked is the fastest Intel processor we've ever tested, at 560Mhz and 620Mhz. At 620Mhz, it crashed consistently on the Business Diskmark test, but as you can see, the Pentium III does hold a clear advantage over the P2, almost as if that 64k L1 cache actually existed!

Intel claims that small architectural changes have been implemented in the P3, and from the looks of the CPUMark score, they've done a good job of it.

Real-World Business Benchmark
CPU speed	Winstone99
Pentium 3 - 620	26.8
Pentium 3 - 560	25.2
Pentium 3 - 500	23.3
Celeron - 550A	22.7
Pentium 2 - 500	22.3
Pentium 2 - 450	21.9
Pentium 2 - 400	19.0
Celeron - 333	16.9

The Winstone results show the same thing. The base Pentium III 500 runs faster than both the overclocked Pentium II 500 and the Celeron 550. Overclocking the Pentium III yielded even higher results, as the increased bus speeds help shoot Winstone scores into the high 20s. This was the last test I conducted at 620Mhz, as Quake and 3DMark decided not to cooperate with our overclocking endeavors, but we'd love to hear if anyone finds a CPU that runs stable at this clock rate.