HAHAHAHAA I like your ghetto mod mate very nice. I once strapped a Pro Meg air cooler to a 5870 card and it was able to do 1100MHz Vantage stable.
OP the first card in SLi will always be way hotter for two reasons. The first reason is the limited cool air that is being pulled into the graphic card. Remember the space between the two cards is quite small and the rear or bottom card will be warming up the air. Second reason the first card does most of the work. Simple as that.
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