What CPU is it? If it's AMD and you are looking at core temps, they are way off at below 40c but at 40c and above they are spot on. When idle, I suggest relying on the socket temp and not the core temp if it's an AMD.
Not sure what monitor you use, but HWiNFO can show socket and core temps.
If you have an FX processor, max temps are
Socket = 70c
Core = 61c