A few degrees Celsius, that'll be the difference between them.
If that matters to you, those few degrees the one with the bigger fan delivers, then choose that one. Otherwise, if you just wanna game and don't really care about the temps, just choose the cheapest one of them both.
Same applies to the TwinFrozr, they'll run cooler as the ones with just one fan, but they're likely to be more expensive and if - as said before - you just wanna game and don't care abou the temperatures, just choose the cheapest.
Wow all of these answers are wrong. The difference between the TOP and Non-TOP 570 DCII is just the factory overclock and a ~$20 price increase. I think I'd personally go for the TOP when it becomes more readily available.
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