Silent Graphics Card

I have not heard of a silent graphic card before, I never hear mine. Since you have a processer fan, 1-2 case fans and possibly more the small graphic fan should not be a noise issue. Is yours making noise?

So, IMHO you should get the video card you want for your needs and I don't feel the fan is an issue.

As for your motherboard:
It's mostly about the video slot on your board. As long as you have the slot AND the correct power supply then you are good to go. Thanks to the fanless thing, the trade off here is a stupid sized heatsink so you will need to make there the slots next to it are empty. I mean, this is silly ridiculous looking:

http://www.tomshardware.com/reviews/fanless-graphics-card-scs3-hd6850,2990.html

To each his own but fanless technology seems a bit early to me just in size alone.

 

As mentioned, you can have a case the size of a house but you still have everything bolting onto a small motherboard. Make sure all the heatsinks clear each other (my biggest concern) and comfortably. When your board was made no one considered a couple of 3 inch heatsinks in the design, I assume. Imaging what happens if your CPU and Video card heat sinks almost touch! You beeter have a good fan pulling that heat out. PErsonally, I wouldn't take the chance unless you are sure