Luis, I don't know how you will respond to this! I reinstalled the apple 500 - as I think I told you. After a couple of days I reinstalled the Giga @ 1.3GHz - with a fan - I also remembered to press the CUDA button for a couple of seconds! I then re-installed Panther and updated it to 10.3.6 with the combined updater from the Apple site. The machine ran perfectly for two days, so I removed the fan - making no more changes. Since then it has been running continously for 6 days at 1.3 GHZ with no problems whatever! I shall post an updated report at Cube-Owner. I 'll keep you updated on any further developments. David.