The best of the bunch is AIDA64 (available here: Download AIDA64). If you want free, however, you'll have to try Speedfan (available here: Download SpeedFan), HWiNFO32/64 (available here: Download HWiNFO) or HWMonitor (available here: Download HWMONITOR).
While Alfredo is working on a better version of Speedfan that addresses these issues, in general, these free applications do not understand how the environmental monitoring and fan speed control IC is actually used in a particular board design. This causes incorrect sensor value display, phantom sensor exposure, etc. and etc. I guess you get what you pay for...
Hope this helps,