Hi I am writing this thread because I need some advice. I have a reference design gtx 680 and I just bought a second zotac for sli but went with the zotac amp!edition because it was cheaper than a reference card. Any advice which card I should put on top? I know the reference design will push heat out the back and the amp edition will most likely push air back into my case based on the look of the cooler. Please let me know what you think, and if its not to much trouble a brief explanation would be great.