As far As I can tell, there are 2 options for "quiet" gtx 970s. Those two would be the...
Asus Strix: http://www.newegg.ca/Product/Product.aspx?Item=N82E16814121899
and
MSI Gaming 4G: http://www.newegg.ca/Product/Product.aspx?Item=N82E16814127832
Both of them turn their fans off during low load and heat situations. However, it seems that 970's as a whole suffer from bad coil whine so I'm not counting them as totally quiet.
The Strix seems to have been more reliable for people, but it has notably lower clock speeds and overclock capacity, partially due to its single 8-pin power input, as the MSI unit has 2 8-pins. However, I'm not expecting too much out of a single 970 so is the difference in clocks even worth it? I saw the video on the strix and the zotac unit outperformed it by miles, but it doesn't seem like it'd be the quietest unit under low loads. The MSI also seems to operate at very low temperatures even under high loads, and will most likely perform closer to the zotac units than to the Strix.
This leads me to question, for what reason would the Strix be worth buying over the MSI unit? Is there any?
Is there anything else leading the MSI unit beyond the Strix? Is one better at being quiet than the other?
As a side note, I don't care much about the aesthetics of each, or the backplate on the strix. As far as I can tell what the backplate does is relatively unneeded. Size isn't an issue.
I've seen a lot of hype for each of these in a lot of situations, but aside from asus' reliable build quality, the Strix seems to lose out in every area.