Technology testing Web site Tom's Hardware Guide today published the first in-depth comparison of the Intel Pentium III and AMD's K6-III. The verdict: the K6-III rules the roost on business applications, but the Celeron is tops for games and floating-point intensive work. The Pentium III, for now, beats the Pentium II solely because of its faster clock speed. Both chips were reviewed in comparable systems and tested with a wide variety of benchmarks to compare their performance with business applications, games and high-end graphics software. Both processors were also compared for the performance boost they give under Windows 98 and the more CPU-intensive Windows NT. For business applications, tested using the Winstone99 business suite, the 450MHz K6-III came tops: it scored 24.3 over the 500MHz Pentium III's score of 24 -- the same score achieved by the Celeron 500/100. The 400MHz K6-III came in ahead of the 450MHz PII and 450MHz PIII, scoring 23.2 to both Intel CPUs' joint score of 22.9, an improvement of 1.3 per cent. Under Windows NT, the K6-III's relatively poor floating-point performance saw it well down on the PIII. The 500MHz PIII scored 34.9 on the Winstone99 business benchmark; the 450MHz PIII scored 33.1 and the 450MHz K6-III scored 32.2. With the Winstone99 high-end NT test, the 500MHz PIII scored 30.2, the 450MHz PIII 28.7 and the 450MHz PII 28.6. The 450MHz K6-III was well down, on 23.4. To compare gaming performance, Tom's Hardware Guide measured 3Dfx Voodoo3 3500 (see 3Dfx unveils Voodoo3 2000, 3000 and 3500) frame rates at 1024x768. The 500MHz PIII scored 46.4m, compared to the 450MHz K6-III's 40.2. Using 3D winbench99 to compare 3D Now! Against the PIII's Streaming SIMD Extensions (SSE), in a lighting and transform test, the 500MHz PIII scored 62.9, the 450MHz PIII 57.1, the 450MHz K6-III 43.1 and the 400MHz K6-III 39.4. Again, the Intel parts come out on top. "My verdict on the K6-III," said Tom's Hardware Guide chief, Tom Pabst, "buy it if office applications are most important to you. Get a Celeron if you care about 3D games or other floating point intensive software. "K6-III is now the fastest PC processor for business applications under Windows 98, but as soon as Intel releases the Pentium III 550, the crown will go back to Intel." As for the PIII: "The Pentium III is only faster than the Pentium II due to a higher clock speed. We will have to wait if there will be any software that can take a real advantage of SSE... For now, I cannot see why anybody has to rush into buying Pentium III processors. Celeron is still the best bang for the buck." ® The Register recommends you visit Tom's Hardware Guide's full set of benchmarks and complete analysis of the new processors and their predecessors.