Palit has shown lots of creativity when releasing their first custom HD 4870 card. The HD 4870 Sonic Dual Edition offers interesting new features like the turbo switch and a dual-fan cooling solution. Also the clock speeds are increased while still keeping full warranty.
Unfortunately the cooling design can only achieve low operating temperatures, but not reduce the fan noise. Actually the card is very noisy, especially in idle, because the second smaller fan is always running at a high speed and is not temperature controlled.
While the turbo switch is a nice gimmick I don't see any reason why someone would run the card at the "normal" setting. The temperatures are within 1°C compared to the turbo mode, and a reboot is required to apply the change. Having a DisplayPort connector is certainly a good innovation but given the low market share these displays have today I can't imagine that many people will base their buying decision on just that feature.
However, I must say I am impressed by the changes Palit made to the AMD reference design without raising cost too much. A mere $20 price increase is very reasonable and shows that there is still a lot of potential in these cards.