Everest, SiSoftSandra,SpeedFan, are all Program-Based applications, which are designed to compliment a Variety of MB's. This leaves alot of room for temp and fan speed discrepancies. Believe what your BIOS has to say, or buy a quality temp monitoring hardware device to get the most accurate readings.
I use the GigaByte EZtune5, SpeedFan, and Sandra here. (average the readings)