Most PWM fans have massive fan ranges which I find annoying on startup too. As a solution I have one of these PWM-DC adaptors:http://www.paqt.co.uk/store/index.php?a ... roductId=5
It allows you to power a DC fan off a PWM header complete with speed control and RPM sensing. Whats more there is a potentiometer on it to adjust the starting point of the fan. You can therefore set it to start at whatever speed you wanted or not start at all until a certain PWM duty cycle is reached. This is far more flexible than any PWM fan and you can connect whatever quiet DC fan of your choice to it. There was some increduility here when I first brought the idea up and disbelief in it working effectively and giving RPM sensing but it really is an amazing little thing and surprising that they are not more prevalent.