For you to set your min/max cpu speed to something other than what the "ondemand" governor would automatically select and use, I think you may need to set your governor to "userspace".
BASH:~/-> sudo cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
ondemand userspace performance
But I may very well be wrong about that.
Edit: OK.. whoops! I misread your above post thinking you said "This didn't work for me." when in fact you said "This did work for me.". You are now entitled to 3 free Nose Thumbs at PabloTwo.