SMART sensor placements differ, usually on main pcb, sometimes outside surface.
They are often very inaccurate and should almost never be used as a measure of disc temps. See spc forums for readings that are over 30C off.
A good measure is your hand. If its much warmer than your hand and you are afraid to touch it, you are more than likely running way too hot (it may work, but you are running a sifnificantly elevated risk of data loss or total failure).