I replaced the stock 350 MHz G3 CPU with a 550MHz G4 from DayStar/XLR8 today.
(paul@pink.local)-(08:33 PM / Tue Jun 15)
[/Users/paul]:: sysctl hw.cpufrequency
hw.cpufrequency: 548515000
It seems pretty snappy and it will mean I can legitimately use stuff like GarageBand now.
The installation was pretty simple, especially since I was already up to date with firmware upgrades. I had to remove a software block that prevented the Blue & White chassis from recognizing the G4 chip/daughterboard: XLR8 provides the software to handle that and it was just like installing an Apple firmware upgrade.
From there, it was a simple matter of unstrapping the old CPU’s heatsink (no grease? wow!), unseating the CPU board (with the ZIF lever), installing and seating the new one, then re-seating the heatsink with the pathetically tiny amount of conductive grease they provided. Seriously, if I had thought to use my digital camera . . . it was the size of the cotton on a Q-tip. That would have been OK, if it was easy to get out of the little bucket, but it adheres admirably to damn near everything it touches.
I was able to get most of it on the top of the CPU core and reseat the heatsink, re-strapping it, and all seems to be well. XLR8 even provides a little software control panel that allows you some control over caches, clock speed, and provides temperature data.
I paid $181 on eBay for it and time will tell if it makes sense: it’s way cheaper than a new system, obviously, but we’ll have to see if it would have been better to save those pennies toward a new one.