As expected, the new 12-inch 1.2 GHz G4 iBook turned in numbers comparable to the 14-inch 1.2GHz G4 iBook we tested back in April of this year and the 10 percent bump to 1.33GHz for the new 14-inch iBook nudged performance up about as much you’d anticipate.
The new Power Mac results were a bit more interesting. Aside from processor count, the new single 1.8GHz G5 Power Mac shares most of the Dual 1.8GHz G5 Power Mac’s specifications, the exception being a slower frontside bus speed. The frontside bus connects the processor to the system controller. On the single processor system, the bus speed is 600MHz, the same as the 1.8GHz G5 iMac. Looking at the benchmark results you’ll see that the new single processor 1.8GHz Power Mac’s performance is right in line with the 1.8GHz G5 iMac.
This is not the first time that Apple has offered a single 1.8GHz Power Mac. The previous model, at the time a higher end system, came with a 900MHz frontside bus, a larger hard drive, twice the RAM, and a price tag $900 higher than the current model.
In an attempt to try and isolate the frontside bus and processor, we took the drive and graphics card out of the new single 1.8 system and installed them into the older, faster bus 1.8. (Note: We test all systems with 512MB of RAM.) In these tests, the older, faster bus system beat the newer system in every task, though not by a wide margin. The difference in system speed really showed up in the Compressor MPEG2 encode test with the 900MHz bus system finishing the task nearly 30 percent faster than than 600MHz bus system.
The message here is not about value; the new Power Mac, at $1499, is definitely a bargain. But it does appear that, when it comes to frontside bus speed, megahertz does indeed matter.