Hi, I'm running a mid/late 2007 Macbook Pro with Mavericks: http://everymac.com/systems/apple/macbook_pro/specs/macbook-pro-core-2-duo-2.4-15-santa-rosa-specs.html When I connect a second display the cpu temp goes through the roof, 90C with the fans at max. When I disconnect the screen the temperature comes down. Temperature Monitor shows that it's the CPU's not the GPU that are getting hot. I've looked in Activity Monitor and there's nothing taking up a large amount of CPU that would seem to be causing this. I've cleaned out the Mac in the last 5 months so I doubt it's a dust build up problem. Any help would be greatly appreciated.