Seems like the WDC WD20EARS-00M are running cooler than the -00S version.
About the mallfuntion temp. sensor, try a HDD fimware update mabe it would fix it.
These WDC WD20EARS where selling for 62,50€ two weeks ago and now they sell them for 89,90€
Regards, Vaako USB Station 2 with DSM 3.2-1968 (altenative firmware) + (IPKG) DS101g+ with DS107 DSM 3.1-1636 firmware DC406e with DSM 3.1-1635 (thanks to Alfredo) DS1511+2Gb RAM with DSM 4.1-2668 DS1512+4Gb RAM with DSM 4.1-2668 + 2x DX510