Noise was measured with a microphone, once with no VGA cooling fan, and then again with the different coolers. The resulting numbers aren't a very useful metric on their own, but they tell an accurate story if you keep this in mind: all of the coolers that measured 3 dB over ambient case noise were almost completely silent, while the stock cooler at 100% fan speed - which was recorded at 15 dB over ambient case noise - was really, really loud.
So we can see that, even though the stock cooler at 100% fan speed reached one of the coolest temperatures under load, it really isn't a viable solution if you value your sanity.
The KuFormula VF1 Plus at high fan speed is a bit more than half as loud as the stock cooler at 100% fan speed, and it's pretty loud, too. But it's something I could live with, at least if I had the speakers turned up or the headphones on. If you absolutely need the best air cooling possible, the VF1 Plus is at least viable at full speed - it's just not all that pleasant to be around.
If you can get things a bit quieter than that, you have a very nice sound level that can be easily ignored unless you're trying to hear it. The Evercool Turbo 2, Thermalright V1 Ultra, Zalman VF900-Cu at maximum speed, and KuFormula VF1 Plus at medium speed are all pretty quiet coolers with good performance.
Finally, the quietest of the bunch: Arctic Cooling's Accelero X2, Zalman's VF900-Cu at minimum fan speed, and the KuFormula VF1 Plus at minimum fan speed. These options are whisper quiet. The tests were done in a very quiet case with a very quiet CPU cooler, and I still had to put my ear right beside the competitors to make sure they were actually running. It's interesting to note that Arctic Cooling's Accelero X2 made produced no discernable difference in sound output when running at stock speeds or with the fan forced to 100% speed.