The fan on my A8N-SLI Deluxe started to make a rather disturbing noise, almost as though someone put cards on the spokes. After a little on line research, I found that Asus is replacing these fans, no charge, no questions asked.
Here is what the Asus RMA department sends as a replacement.
Tha fit is a little tight, but it clears the exposed copper by about an 1/8".
If you have problems, first call tech supprt and open a ticket. Then call the RMA group in reference to that tickaet and they will send you the new fan USPS.
I did get another tip from a friend of mine. If your heatsink/fan is "ringing", take off the top metal trim piece attached with the four tiny screws. That may help. Also, I did find that many repacement coolers availabel have to be modified, ie attacked by a Dremel tool, in order to fit. The pin holes are just slightly closer together than the standard "chipset" heatsinks available at your local Fry's or CompUSA.