While idling the GPU temperature ranges from 26 to 28 degrees Celsius. Oddly enough the fans are silent in idle mode. To be fair they are only audible once you get really close to the chassis, otherwise you won't hear them. However, users looking for absolute silence should look elsewhere.
If on the other hand you plan to use it in a more or less standard system, the card is quiet enough, as you won't hear it next to your CPU cooler, PSU and other components. Sadly though we were not able to silence the fans by reducing the RPMs, because the 750 series use a 2 wire fan, so the RPM must be controlled by voltage. Note that the minimum fan speed is set at 42% RPM and we could not lower it. 42% (or around 1800RPM) is the lowest voltage the fans can operate at. Keep in mind the 42% does not really correspond to noise level when compared to other cards because the RPM that is tied to 42% will vary from card to card.
Once we started gaming the temperature shot up to a rather modest 49 degrees and the fans did a good job. Interestingly, under load the GTX 750 Ti FTW is silent compared to most of the cards we had a chance to test so far. It's a pity that it's not completely silent in idle.