Click on Configure - Go to the Speeds tab - Select a Fan by clicking once on it - Change the minimum and maximum speeds at the bottom of the tab (you can set both to 70% if you like). Select the next fan and change the min and max, continue as needed then click OK
If the automatically variated checks are off on either the main screen or the speeds tab the fan speed will not be controlled by speedfan.
If you decide you do want varying fan speeds take a look at this thread for more settings you may need to consider. http://www.silentpcreview.com/forums/vi ... hp?t=42526