My Thinkpad T420 was running hot, I cleaned it and had new paste added to the CPU. Since then it has been running very cool.
Plus as jggimi suggested, I use obsdfreqd. For what it is worth I use these setting in /etc/rc.conf.local
Code:
obsdfreqd_flags=-T 73,65
apmd_flags=-L -Z 5
remember to use rcctl(8) to set the flags