Just call or write email to the manufacturer and ask them to send you a new fan... I have done this before with an Abit motherboard..
The fan started to make a grinding noise... sent them an email with my address and they mailed me the fan in 3 days time at no charge.
They never asked for proof of purchase or anything
As for your video card RMA return to manufacturer??? I would think that you need to provide proof of purchase to get approval for repair or replacement... do you have the orig receipt?