Running hot - lid up or down ?

[The Mercurian]

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 ?

 

[Aodhan]

I run mine all the time closed, including for gaming. Stays nice and cool. Cooler than my 2009 MBP. I also use mine in a BookArc, but I don't believe that makes any difference in cooling, I was getting the same temperatures before I got the BookArc and it was just sitting on my desk.

 

[The Mercurian]

Yeah I do sometimes use mine closed and that fine. But I will be doing heavy duty math on it where it will be running at 100% for several days. At 100% the top left corner gets very hot to touch and I was worried that could damage the screen over 3 or 4 days of 100% running.