I have the cyclone. It's definitely not silent, though generally when I'm pushing the card I also have the sound up, at which point I can't hear it much. At idle it's quiet, but still a bit louder than my computer's baseline (which is nearly silent). All four slots in my case are used, so perhaps I'm crowding the card a bit, which might make the fan ramp up more than otherwise. Overall I'm not displeased with it. If you can wait a few months, you can probably get a 7000 series for the same performance and less wattage, which of course equals less heat and noise.
Used to have a cyclone too and it's a brave little card that OC's very well. It's not silent at all but gives a gentle humming noise when pressed hard. For the price/performance ratio I always recommend it.