Your computer can tell you the temperature of the hard drive to the degree, but how exactly does it perform such a trick? Read on as we dig into the hardware and software elements of system monitoring.

Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-driven grouping of Q&A web sites.

The Question

SuperUser reader Royi Namir needs to settle a dispute with a colleague:

I had an argument with a colleague about :

"How do software programs (i.e. hwmonitor) determine the temperature of the hard drive?"

I said that there must be a thermometer inside the HDD and the data (via SMART) is passed as regular info to the soft which wants that info .

He said : "No. There is no thermometer inside the HDD. You have to plug it as another hardware on your HDD. All the software uses statistics about heat from the RPM info"

So, how do software programs like hwmonitor, determine the temperature of the HDD?

How indeed? Let's dig in and get to the bottom of this friendly dispute.

The Answer

SuperUser contributor Renan backs up Royi's assessment:

The hard drive has a temperature sensor (or multiple temperature sensors - they might be used for internal control, self-test etc...) inside, and this data is passed through SMART (in fact, this is a standardized SMART parameter).

If you're curious about the SMART system and everything it is capable of reporting, we highly suggest checking out the link above. You'll find there are variable for everything from temperature to spin time to errors and everything in between.

Have something to add to the explanation? Sound off in the the comments. Want to read more answers from other tech-savvy Stack Exchange users? Check out the full discussion thread here.