Hello out there. I hope this thread helps some body out there. A few months ago one of the logic boards in my G3 ibooks was acting particularly strangely. Most of the time it would boot up with out a problem but about 15-30 minutes into operation it would suddenly and randomly crash inexplicably. After scouring the internet for answers and analyzing the heck out of that ibook I finally came to the conclusion that I had a bad onboard chip. Thanks to the thread how to disable dimm0 on an ibook 800? I figured out how to disable the onboard ram chip. As Varu (scroll down the page) explains, the memory in the ibook consist of banks (G3 ibooks have 4) of TSOP chips, that receive power from the board at certain pins. By disabling the power for one of the memory banks you prevent the ibook from being able to use any of them, thus disabling the faulty memory. Be aware this is a point of no return modification (well maybe). However, instead of the 1,18, and 33 pins for the G4 you must disconnect 1,14, and 27 for snow white ibooks. If done correctly, the ibook should not be able to boot and will beep three times indicating that there is no accessible memory. At that point you simply place a memory stick into your ibook and it should run as good as new. Below is more information I found usefull in my search.

Open Firmware. (Its your friend) Use these links to help diagnose any PPC computer system.

Technical Note (Apple Site) Show you how to manipulate memory and view other properties in firmware

Kernalthread.com These guys do it too but have some more info

SunMicro (for NVRAM) Teaches you how to manipulate and store instructions in the NVRAMRC. Upon booting NVRAMRC (if set up to do so) will always be read and any valid instructions contained within will be executed automatically.

Firmware Instruction Firmware uses the FORTH computer language and so here is a list of other functions of Open Firmware.

Things Apple Doesn't Want You To Know. (Sort of) These are some links that is buried within apple's site and are very difficult to find if you do not know were to look.

Apple Hardware Products This is a list of every single (I think) apple hardware product from iMac to IIci prior to the intel conversion. For each one there is an HTML or PDF file with a detailed description of each model from ports to CPU's.

Hardware Diagnostic CDs This is list of all the Apple Hardware Test CDs for all of computers that used them. So do not worry if you do not have a copy. Please be aware that you must use the disk utility to burn an image of the CD. Roxio Toast does not work. Search the internet for more instructions (hey I can't do everything for you).

Other

Boot Keys Useful boot key instructions. Use these to determine if other hardware is at fault such as hard drive.

Memory Datasheet This is the datasheet I used to disable the memory.

Rember Memory Test Use this app to test your ram.

Finally. Symptoms I experienced that lead me to believe it was the onboard ram was that after everything was removed and while exploring the firmware I would get this constant read memory error or something like that every time. This came after the fact that after running rember, or running Tech Tools, the computer would always crash.