The CPU may have the most influence on a computer’s overall performance, but this isn’t the only factor that determines how quickly your Mac runs. While a processor upgrade will certainly speed up a Mac, it won’t make your machine as frisky as a new Mac with a faster system bus and higher-performance video circuitry. Newer Technology’s 433MHz iMaxpowr G4 offers a case in point. This upgrade increases the overall performance of the iMac’s first four revisions and turns in Speedmark 2.0 scores nearly 50 percent faster than those of a 233MHz Rev. A iMac. Unfortunately, the iMaxpowr can’t match the overall performance of a 400MHz Power Mac G4 because of the bottlenecks inherent in the original iMac’s bus speed and poky video circuitry.
Because Photoshop takes advantage of the Power Mac G4’s Velocity Engine technology, our iMaxpowr G4-equipped Rev. A iMac fared far better than the same iMac with its original 233MHz G3 processor. Yet the 400MHz Power Mac G4 performed better still, thanks to its faster bus speed and video card. The iMaxpowr’s extra 33MHz did pay off in our SoundJam encoding test, however; the iMaxpowr-equipped iMac bested the Power Mac G4 by 7 seconds. And as you would expect–since 3-D gaming performance relies more on the graphics chip than on the processor–the iMaxpowr iMac produced a scant 2.6 frames per second in our Quake III test, compared with the Power Mac G4’s 34.5 frames per second.