[iBook] uh-oh

[James Bamkin]

Help, My Ibook G3 has gone funny. when i switch it on it will bong but
then make no further sounds, when I try again it will some time beep
then bong and then start the white screen where the apple should
appear but nothing else, other times it will come on load OS X 10.2 as
it is supposed to and run fine untill Ituch it and then the scrren
messes up and and i won't do anything. from a quick we search I did
now it appears to be the graphics chip over heating, does that seem
right? I guess this means a new logic board, but how much does that
cost and I guess that is a professional task.
Hope you can help.