Gigabyte Fanless 4850+ Antec Sonata Elite, Possible problems?

Hello, I am buying parts for my new computer I'm building, and it is going to be my first build (Asus P5Q, Intel E8400, 2x2GB Ram, Samsung 1TB Hard drive, Antec Sonata elite). The main reason I am so choosy in my parts is because I want this to be a Hackintosh. The parts I have are all compatable with OS X so I am fine, but I am unsure about the video card. The 4850 is fully compatable with OS X but the specific model I want ( http://www.newegg.com/Product/Product.aspx?Item=N82E16814125258 ) Is fanless. I have the Antec Sonata Elite, and it has a fan that is mounted by the video card horizontally, and a fan in the back like normal. I do not know if this would be enough to keep the card cool. I chose this card because I NEED the HDMI with sound support as my TV is impossible to work with with RCA and DVI to HDMI converter. GIGABYTE looked like the best brand there and so I chose that one. I also have a 550 watt PSU is that enough? Thanks in advance!

Well, one of the reviewers said his Sonata II case (one rear fan) the card was stayed cool enough to function stably. That's probably the closest indicator that it should be alright in yours.

The 550W supply will do fine.