Electricity, by its nature, heats things up. And heat, by its nature, can damage electrical circuits. Everyone with a computer has to work within that paradox.
I've written about overheated PCs in the past, but that was in the context of PCs that overheat so badly they shut down. But heat can cause problems before the crucial stage. Too much heat can reduce the CPU's efficiency and wear out components faster than necessary.
So it's best to keep an occasional eye on the temperature, especially if the PC feels hot to the touch, or if the fan seems to be working overtime.
[Have a tech question Ask PCWorld Contributing Editor Lincoln Spector. Send your query to answer@pcworld.com.]
If you suspect your PC is overheating, download Priform's Speccy. The free version will probably be sufficient; it's the one I use. There's also a free portable version.
The main Speccy window provides plenty of information about your hardware. Temperatures stand out in bright yellow or--if it's on the high side--deep orange text.
If you select View > Options, you'll be able to switch the temperature display from Celsius (Metric) to Fahrenheit (Imperial).
The System Tray tab allows you to make temperature information always available in the notification area.
But an orange-text temperature only implies that you might have a problem. To get the real information, you'll need to know the make a model number of your CPU and internal drive (be it a hard drive or SSD). Don't fret, you can get them easily off of Speccy.
To find out how much heat is too much for your CPU, go to CPU World and search for your processor. Search for your processor's general brand name--for instance, i5 instead of Intel Core i5 2520M @ 2.50GHz. Once you're on the right page, scroll down to find your particular CPU. Click on it. Search the resulting page for temperature.
The heat level isn't all that big a problem with hard drives. A Google report on drive failures determined that "temperature and activity levels were much less correlated with drive failures than previously reported." But any drive, whether spinning disks or solid-state, can be damaged by heat, so it's good to be safe
You can almost certainly find your drive's manual online. Once you've got it, search the PDF for the word temperature. You'll find the right numbers.
If your computer is running hot, see the instructions from my previous article.