As an official statement to stop people quoting bits here and there this is our official policy on coil whine below:-
OcUK will accept an RMA for a card which has coil whine in extreme circumstances which we consider to be audible on a quality single rail PSU of gold rating or higher. Audible as in coil whine in normal usage and gaming which is audible above case fans in a closed case. Coil whine in benchmarks is not considered as a fault. It's not actually a fault in the hardware as such if a card whines, it is inherent in graphics card design, but we will class it as a fault for cards which are clearly audible in normal usage (gaming). For example two identical cars, one will consume upto 1l of oil every 1000 miles and the other one consume nothing, this is not considered a fault by the manufacturer and it is operating within specification.