I was doing some rendering and I realized that the random restarts were caused by heat. Under Tiger my fans would be going full speed during a render, however under Leopard they are barely going 2500RPM with the CPU fully utilized. I never had an issue with the fans under Tiger, in fact I had done some huge render jobs before upgrading to Leopard. Once Leopard installed I noticed random reboots, then i realized it only happened when the CPU was really taxed. At first I thought a bad memory module, ran AHT 2 times under "extended" with no errors detected, and repaired permissions. Then I downloaded a app that shows the temp and fan speed. I realized that the CPU was getting 70+C temp and the fans were going no faster than 2498k RPM, once it reached around 78C the machine would restart. The fans on my MBP have worked fine until I installed Leopard, This may be in the improper forum but my issues started once I installed Leopard so I am pointing the finger at that. I installed smcFanControl and forced the fans to a minimum of 6k RPM, I could do my render fine with no random restarts which tells me that what I thought was true, the fans aren't kicking in when they should. My MBP is out of Apple Care, but I think I can call them since I believe this to be Leopard related? Any Advice/tips? Specs: OS X 10.5.1 Model Name: MacBook Pro 15" Model Identifier: MacBookPro1,1 Processor Name: Intel Core Duo Processor Speed: 2 GHz Number Of Processors: 1 Total Number Of Cores: 2 L2 Cache: 2 MB Memory: 2 GB Bus Speed: 667 MHz Boot ROM Version: MBP11.0055.B08 SMC Version: 1.2f10 Mods if you need to move this please feel free, I just feel this is Leopard related.