David Schlachter

Macintosh PowerBook G3 PDQ 400 MHz processor?

Dec 4, 2018

The PDQ / Wallstreet II PowerBook G3 may appear in System Profiler under Mac OS 9 to have a 400 MHz PowerPC G3 processor. This model only shipped in 233, 266, and 300 MHz configurations. Third-party upgrade cards were available since daughter cards with the CPU on them were interchangeable between various PowerBook models, and it is also possible to overclock the processor. I acquired one of these machines and wanted to know if the processor speed was actually as reported:

System Profiler showing a 400 MHz G3 processor

I read that some versions of System Profiler mis-report the CPU speed. The machine is currently running Mac OS 9.2.2 from the Mac OS 9 Lives Universal Installer, with System Profiler version 2.6.5. I have a Macintosh Server G3 install disk, so I rebooted from it into Mac OS 8.5.1. System Profiler 2.1.2 shows the same speed as in Mac OS 9.2.2. I also booted from a Norton SystemWorks CD which reported the same CPU speed in its included System Info application.

With software reporting consistent results, the next step was to take apart the machine to examine the actual CPU daughter card (click images for larger version):

PowerBook G3 PDQ (Wallstreet II) 266 MHz CPU daughter card, top PowerBook G3 PDQ (Wallstreet II) 266 MHz CPU daughter card, bottom

Comparison with the cards shown by this page on overclocking (English via Google Translate, and source) shows the same resistor layout and part numbers as on the original, unoverclocked PDQ 266 MHz processor. (Note the sticker on the second image that specifies the speed also)

Additionally, I was able to run a CPU benchmark with Norton SystemWorks that compares the processor to other Mac models:

Norton SystemWorks CPU benchmark

Conclusion: even though it's displayed in software as a 400 MHz PowerPC G3 processor, this PowerBook G3 PDQ actually contains a 266 MHz processor.