550Ti has about 116 Watt of TDP. I personally will not recommend to passively cool such a card, though it will not overheat however will considerable lower the lifespan of the card as it will be operational between 80-95 C.
You can achieve super silence using an AC Accelero Xtreme III.
I am not worried about the temp of my card (idle-40C & load -72C) , I would like to build a silent pc .now I have 1 x 120mm & 2 antec 80mm fans in my case .
I am not worried about the temp of my card (idle-40C & load -72C) , I would like to build a silent pc .now I have 1 x 120mm & 2 antec 80mm fans in my case .
In that case go for the same that I have suggested, as it is super silent.
Where do you live, that will also determine average ambient temperature at your location, Maybe i can advise better.