They differed, however, on the best way to vault that performance hurdle. At San Francisco's Macworld Expo this month, IBM Microelectronics Division of East Fishkill, N.Y., announced a 275-MHz version of the G3 chip. The other PowerPC partner, Motorola RISC Microprocessor Division of Austin, Texas, offers a 250-MHz processor. Although this process is not universally accepted by system vendors or users, industry insiders agree most processors are capable of running above their rated speeds. There is usually a wide range of performance found in chips from any given production batch, analysts said.
Manufacturers test the finished chips at various speeds, certifying the performance of each one.
The cards also provide an acceleration mode that lets users adjust clock speed. Tony Lux, MacWorks director of technology, said the company first tuned the card's 250-MHz G3 processor to 320 MHz but backed off to 307 MHz, where it determined efficiency was best. However, other vendors have decided to stick with the manufacturer's rated speeds for G3 processors. There's no easy way to determine the margin of error. While Newer used tuned processors for its PowerPC 601 upgrades, the company's G3 cards will stick with the manufacturer's rating, Kasten said.