So I'm doing a bit of number crunching on my MBP. IT will be running an running hot over a couple of days. Is it better to do this with the screen open as in normal use, or with the screen down and an external monitor attached ? Does it make a difference to the fan performance ? I don't want the thing powering off due to an overheat. If its closed does the heat affected the screen ? I mean it gets quite hot in specific places. THat cant' be good for a screen, can it ?