Processor upgrades touted at 1.4 GHz, based on (1.33 GHz max) 745x chipset; Not "over-clocking"
Processor upgrades touted at 1.4 GHz, based on (1.33 GHz max) 745x chipset; Not "over-clocking"
Sonnnet (and other processor upgrade manufacturers soon to follow) has begun offering a new 1.4 GHz processor upgrade based on the 7457 series of Motorola G4 chips, which use 2MB DDR (Double Data Rate) L3 backside cache. Also offered are 800 MHz, 1 GHz, and 1.2 GHz flavors. However, the PowerPC 745x series of chips maxes out at 1.33 GHz according to Motorola's specifications.
At first it may seem that Motorola is debuting slower chips than its previous iteration. After all, Apple's fastest G4 system contains dual PowerPC 7455 processors rated at 1.42 GHz.
Upon closer inspection, however, you will notice that Motorola only rated the 7455 chip at a maximum speed of 1 GHz. This means Apple exceeded the stated clock setting, moving the system to a 40 percent faster frequency but maintaining reliability.
It is not yet clear whether or not this type of expanded speed ceiling will exist for the 7457. It uses the 0.13 micron nine-layer metal, rather than the 0.18 micro process used for the 7455, and also will almost certainly be a speedier chip thanks to its 512 KB of on-chip cache compared to the 7455's 256 KB.
So rather than "over-clocking," Sonnet actually took an ostensibly conservative approach rating its top chip at 1.4 Ghz, just 67 MHz faster than its data-sheet rated speed.
Sonnet says "In order to work in both 100 MHz and 133 MHz bus speed machines, the new Encore/ST includes advanced technology that automatically detects the bus speeds of its host machine and sets the performance of its processor accordingly."
The card supports Mac OS 9.2 and Mac OS X. The Encore/ST G4 1.4 GHz has an estimated street price of US$600. The Cube Dealer Installation Kit for this model will be available soon, and has an estimated street price of US$60. Feedback? Late-breakers@macfixit.com.Resources