Thank you for the advise trag! I did notice that the old heat sink grease was dry. I have some new grease so I will replace the old one.

Something else : I managed to install system 7.6.1 on this machine. Every time I restart the computer, my changes from the Views control panel (icons size) are reset. Nothing else is reset (time, sound alert...). Where is this setting saved? Is this due to a bad install or a hardware problem?

Thanks!