Im running a asus gtx460 and it is silent. on idle it is running at a temp of 24 and on load it has reached 53, even at 53 i still cant here the gpu.
My antec tricool fans are louder on min than the fan on the gpu.
my mate has a msi gtx460 and that is just as quiet as mine and that has been oc'ed slightly. i would speak to the supplier and see what they say, see if they would class it as a fault