My 733 Quicksilver has this problem: originally it just went dead, with a clattering of the big fan under the power supply.
I replaced the p.s. and had to pull out the battery to reset the logic board, it then started fine, it worked fine for some hours yesterday night, then overnight started restarting itself every 5 minutes, whether I am using it or not. In that short time things work, except that Safari would get stuck loading pages, which did not happen in IE.
I had not changed anything either software or hardware for a while before this, and permissions were repaired recently. the SMART test reveals no HD problem. Also cloned the HD to my powerbook last night, works flawlessly, so it is not a sw problem.
10.3.5, 733 G4, 1.5 G ram,
Many thanks for your help
