I know that they make water cooling blocks for the Fermi cards, but is there any company which makes aftermarket air coolers and heat sinks for the GTX 480?
The Fermi is notorious for extremely high temperatures. So, (even at stock speeds) an aftermarket cooler shouldn't hurt. I do know that countless aftermarket fans/heat sinks exist for the ATI Radeon 4xxx and 5xxx series graphics cards.
I don't think anyone can certify the lifetime of the cards. The ATI 5000 series aren't that much off, maybe 10C depending on airflow and load of course. But what is 10C worth? I personally have no idea.
The cards are backed up by warranty, so im sure the engineers got it all figured out. Won't want the company to incur too many liabilities right?