That fan is a different configuration than other versions of this card I've seen online.
Is it pushing air through the heat sink (away from the DVI connectors, blowing towards the front of the Mac), or, is it sucking air in from the heat sink and blowing out the side of the card (up, when installed in a Mac) ?
I'm concerned that if it's pushing air towards the centre of the Mac, it is working against the designed flow from the Mac's fans. Perhaps it is running at such low speeds that it doesn't matter, but I'd like to keep the entire system cooling at greatest efficiency.
Also, I wonder if the fans on this 3870 are quieter than the post-firmware update 2600?