before have you try sensors-detect to configure lm_sensors
if not better because nothing was found
first you need to find what is the chip on the motherboard searching the internet and dell support.
second there is two solutions:
- th eversion of lm sensors comming with you sme is too old and simply upgrade it will solve
- the version of lm sensors is too old AND the kernl support of your chip does not exist until a kernel version > 2.6.9 ... then you need to update your lm sensors and compil you own kernel >= to the fisrt version that support it (check lm sensors web site to know this) .... be careffull it is hazardous to try to compile your own kernel as you may break the consistency of your SME
alternatvely you can simply ignore this feature