Mobo temp sensors suck for accuracy. However, they are good at telling you Temperature deltas. For instance, what is your load temp vs. Idle temp. If the temp doesnt change that much, that means your Zalman is doing its job.
For instance, my cpu idle is 48 and load is 53. If it were in a different mobo, that could be 58 and 63 or 32 and 37 etc.