My 867 Quicksilver is having overheating problem. It has happened 3 times in past week. First, it happend while I was watching DVD, it just shut down on its own and would not reboot until it cooled down for a while. Then next two instances, it would just shut down on its own while I was simply web browsing and listening to a CD. This is quite a suprise for me because this sort of thing never happened in previous Macs I've used, Quadra, PowerPC 8100, G3 300, G4 DP 500, etc. Quicksilver is in well ventilated place and considering it is Winter time, I really doubt environment temperature is a big issue. I'm already thinking of placing an order for PCI slot fan from 3D Cool. Do any of you have a recommendation for any other means of cooling my Mac? Any CPU fans I can use? Any input would be greatly appreciated.