i think the main reason why they have those limiters on power consumption is because they were trying to bring down the temps and they did amazing job with that i havent gone over 65c yet ever with burn test and thats with 900/1800/2000 overclock my smaller and a lot less powerful 5770s ran like 80c-85c overclocked in burn test
It has to do with how much power is being drawn as well as heat. There have been ways to cope with overheating for years, now adays its nearly impossible to kill a card by overheating it. The real danger is overtaxing the VRM's, which is what you need to watch out for with the 570 (580 I believe is ok because it uses 6 VRM's instead of 4.
I bet you if you try a game, it won't underclock like its been doing in Fur. Forget about furmarks, its a pointless power virus that makes you think you need to lower your clocks, when in reality they're fine for gaming and normal use.