Temperature Sensors

Are the temp sensors found on Socket A motherboards like my MSI K7T Turbo and Turbo2 of any use? I've read that their accuracy is poor. If so, how can you accurately measure chip temps?

What about motherboard temp sensors? Are they just as bad? What exactly on the motherboard are they monitoring?

I've read that Intel incorporated temp sensors into their CPUs, has AMD done so in their new line of chips?

Thanks for reading this.