Upgrading logic board on a ibook G3 700Mhz

Check this guide on how to remove the logic board. If the 800mhz logic board is the same, it should work. Somebody correct me if I am wrong. My best friend once exhchanged an iBook G3's logic board with a iBook G4's logic board and it worked.

Have you tried the fix described here? Basically it involves inserting something a few mm thick in between the plastic casing and the metal shielding the logic board, just under the video chip. Helps keep the video chip in place. I just tried it on my iBook last weekend and it's been working fine all week (after a year of being "dead"). I did have to do it twice, adding a thicker piece the second time since the first time it fritzed out after about 8 hours.

Unfortunately I don't know if there are any issues regarding the 800 MHz board in the 700 MHz case, though I kind of doubt there would be. If you go that route, definitely be sure to use the guides at http://www.ifixit.com/Guide/ as recommended above.