I had the 7970 XFX DD from the first week the 7970 released, was always relatively silent (up to 50% fan) and cool (core below 60c and VRM's being below 75c in worst stress tests) but there were many reviews saying the card was running hot and loud (some French site was saying VRM's were above 100c). So I guess they have issues with sitting the cooler properly on all their cards. Personally I even removed the cooler and place IC Diamond paste on the core an new pads on the ram modules and vrm's and the temps were about same but fan speed was then 45% max after that TIM change (even lower than before). OFC 50% and 45% is nowhere near inaudible, but its perfectly "silent" for a full power test with OC'ed card at 1100mhz+).
But yeah, issues with XFX DD cooler are pretty frequent it seems, but I'm sure if you resit the cooler and replace TIM on the chip it will get much much much better (just make sure you don't break the thermal pads so u can reuse them.)
EDIT: my flatmate uses my card now, its still silent.