In a normal environment, you should be able to leave a game console running for over a week without shutting it down. Even when running a game, (in a perfect world) the game shouldn't crash or show any weird behaviors. The version of the hardware/firmware can also effect the lifetime of your console. I would guess that the ps3 slim generate less heat than the huge shiny behemoth. But heh, lots of people burned down their consoles (including xbox) in a couple of weeks by playing normally. I've got the 2nd wave of ps3 (right after they cut the price for the first time) and frequently leave it on for the whole day with a room temperature around 29-30 degrees Celsius and the damn thing is still working like new.