I'm not an expert but i would guess that heat and overvoltage is the quickest way to kill a cpu. Heat is ok aslong as you have a cooler that dissipates it. As for overvoltage thats just bad anyway, it stresses the physical compent like bending a Dr Pepper can too much causes it to split.
I use the Antec 900 & Ultra Extreme 120 and think it's one of the most awsome looking cases about
, aswell as being great at cooling my pc and indirectly cooling my mouse hand during games.