Hi there, can anybody help or suggest? I have my PB and it has incredible display issues. I was/am running Leopard though you cant see it anymore. For the majority I get the startup screen clear(with apple) and then leopard screen is a mess, but its in little 1cm blocks of individual and repetative distortion. Its not white lines, just identical little scrambled boxes...very symmetrical. I routed through VGA and get a better looking screen but still screwd up and the same thru Svideo. The odd thing is, occasionally, even though the screen is a mess, if I open up 'about this mac' or 'system preferences', they are crystal clear....for a few moments.
I have done the following, repair disk, fsck, reset pram, changed ram to official mac, new inverter board, new display cable, new inverter and antenna cable and none has changed it. I recently decided to take out the logic board and it appears that the previous owner did the same but I dont think he reinstalled the board with the thermal paste..or maybe did but if so, he did incorrectly. I dont have access to the original(and apparently one type only) hardware test dick for this model. I am really hoping its not the logic board....as there is just no way I can afford a new one. Kinda happy right now that I kept my trusty 800Mhz G4 ibook as a backup!
Anyways, any light on the subject would be greatly appreciated. Thanks
Oh, I also tried to back it down to Tiger...and when I install the OS disk and restart.....it only returns to a pure blue screen(crystal clear mind you) but it won't let me remove leopard.

Does it have the same problem on different screen resolutions? You can try a lower res and see if it fixes itself which may mean a VRAM problem.

Either way though, it is most likely a problem with the video chipset on the logic board especially since you have the same issue on external displays.