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Why Is My Computer Hot and Loud?

Heat is the enemy and can come from many sources.

Several components in your computer use power and generate heat in proportion to how they're used. I'll review the two biggies.

Hard drives get hot because of moving parts inside. But does anything else contribute to their heat output? Does a 1TB hard drive produce more heat energy than, say, a 500GB hard drive, all other things equal? And if a 1TB hard drive, for example, is running nine applications at once, is it producing more heat than if it were only running two applications?

In other words, is my computer burning more calories when it’s thinking harder?

Yes, it is.

Strictly speaking, drive capacity doesn’t have an impact, but the internal characteristics of a drive certainly can, including spinning hard drives as well as SSDs.

But there’s more to it than just the drive.

And while I suspect you didn’t mean it that way, calories is an accurate term.

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Hot and loud computers

Computer components generate more heat the more intensely they’re used. If your computer is working hard on something, be it CPU- or disk-based, that can result in more heat generated and the cooling system kicking in. Sometimes the fans used by those systems are loud when running at full speed.

HDDs and power

In older HDD drives, a spinning disk generates a certain amount of heat and uses a certain amount of power. The key is that this energy consumption is constant: unless you set power-saving measures like “shut down the drives after X minutes of inactivity”, the drives spin continuously at a constant speed, using a relatively constant amount of energy and producing a relatively constant amount of heat.

It’s the arms that generate the heat. The arms hold the magnetic read/write heads that move back and forth from the inside to the outside of the magnetic area of the disk. The more you use the disk, the more the arms move. The more the arms move, the more heat they generate.

SSDs and power

SSDs have no moving parts, so you might assume they don’t use as much power or generate as much heat, and that is true.

However, electronic circuits, including those inside an SSD, generate heat as they’re used. Much like a spinning hard disk, the more you use the disk, the more the electronics generate heat.

This is normal. The best way to describe it is that this is just how electronic components work. (Research is always going on to make these components use less power and generate less heat while still performing their tasks.)

Of calories and diets

While we typically think of calories in terms of the food we eat and the weight we’re not losing, the use in this context turns out to be quite accurate. A calorie is a measure of energy. Heat is energy. Hence someone could measure the amount of heat generated by your CPU and hard disk in calories if they were so inclined.

Capacity and power

On one hand, capacity has little to do with how much heat a disk — be it an HDD or an SSD — generates.

And yet, there can be a correlation. A larger-capacity HDD, for example, might be used more or might need to move its arm around more frequently to access the data on the drive. A higher-capacity SSD will have more electronics on it, which may also be used more intensely.

In both cases, a little extra heat might be generated by larger drives, but not a lot.

Besides, they’re not the biggest problem.

The CPU and Power

Generally the biggest source of heat in your computer these days is the Central Processing Unit, or CPU.

It’s the part that does the computing.

If you’ve ever looked at Task Manager or Process Explorer, you’ll find that your processor is mostly doing nothing. By that I mean the processor usage measure is often below 10% or even lower. As I edit this document, my processor is having a hard time getting over 2% usage, and that’s mostly to update the display of CPU usage. That means that 98% of the time, it’s doing nothing. It’s “idling” — hence the “system idle process” you often see listed.

When the processor is working hard, it uses more power. The harder it works — 10% usage, 50% usage, 90% usage to a processor fully pegged at 100% CPU usage — the more power it uses. And the more power it uses, the more heat it generates. So, like the disk, a busy CPU is a hotter CPU.

It’s important for the heat to go somewhere so as not to damage the processor. That’s why almost all computers, desktops and laptops alike, have fans that start running when the processor starts to heat up. Many are variable speed, and it’s not uncommon for a hard-working computer to sound like a small aircraft taking off as all those fans run at maximum speed to keep it as cool as possible.

Do this

If your computer is overheating or just running hot:

  • Make sure all air flow paths are clear. (And not clogged with Corgi hair, as happens around here.)
  • Use Task Manager or Process Explorer to examine what your computer is doing. Most often a computer is hot because it’s working hard. If that’s unexpected, you want to understand why. It’s not common, but occasionally it can be a sign of malware.
  • Check your computer’s hardware, specifically the internal fans, if you can. If they fail or become clogged with debris, they’ll be unable to do their job.

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12 comments on “Why Is My Computer Hot and Loud?”

  1. This may not be completely relevant to this article, but it does link to another recent article about crashes.
    I had a heat problem with my laptop (before it died completely).
    Sitting idle, my laptop would BSOD after 5 – 10 mins due to the faulty memory in the graphics card overheating.
    Yet, I could ‘use’ my laptop for hours sometimes, without a single crash – simply due to the fact that the CPU’s would generate heat and trigger the fans which would cool everything, not just the CPU’s…

    Sometimes, heat is your friend – but not often :/

  2. I’ve never understood why people like those enclosed cabinets for their computer. It just means the system is more likely to overheat, since you’ve basically placed it in an oven. Sure, the computer vents its hot air out of the chassis, but it just brings the same hot air from the cabinet back in.

    I have seen some (though far-between) cabinets with fans to exhaust the air from within them.

    Also, this is why you need to make sure there is some clearance around not only the exhaust (typically from the power supply area), but also the intake, somewhere else on the chassis, to permit cooler room air to enter. And, to occasionally vacuum off the dust bunnies which are sure to accumulate around the vents.

  3. As I said before, None of the people near me follow Ken B.’s advice. I do for me and someone else’s computer. One thing I keep thinking about is my Aunt’s Mac. The only opening I see is a small round hole in the back, last year after her hard drive died and it was replaced by someone else.

  4. Alternately, today’s more powerful, faster, denser CPUs often use less power and generate less heat than their predecessors because they are engineered to do so… this is one source of longer laptop battery life (not better batteries, but better usage of the limited power they contain ;-).

  5. Not completely certain on this, but my understanding is that the calorie is a unit of heat measurement. It was picked up by dieters because the metabolism of food — primarily a variety of slow oxidation, i.e. slow burning (!) creates heat, which is precisely commeasurate with the amount of energy the food contains. You get exactly the same amount of energy from actually burning the food as from eating it — only when you eat the food, all that energy goes into your body rather into producing smoke and flames!

    By the bye — completely off-topic, I know — but this explains why alchoholic beverages are always so caloric: you are drinking what is, by definition, a flammable liquid. (Note however that most beverages are dilute, and are not therefore in a flammable proportion — the beverage must be greater than 57% abv or about 114 proof under modern measure, for that. Nevertheless, alcohol itself is, by nature, flammable.)

  6. Glenn P. I love your science but it’s kinda mixed up. Calorie is a measurement of energy, not heat. It can be measured in many different units – in the metric world of food for example, we use Joules (actually, kiloJoules) to describe the energy potential of the system. The system can be chemical, mechanical, electrical or thermal.
    1 kilojoule = 239.005736 calories.
    Heat is measured by scales of temperature such as Celsius, Fahrenheit and Kelvin. However, in the process of expending energy (converting it into power (Watts, Horsepower, etc,) heat is created and…well, it gets very technical here and my old physics teacher was much better at explaning it LOL

  7. Hi Glenn and David and all others reading this. I am an old physics teacher (yes!) and I’ll try to explain things a bit. When you are burning food outside your body it will give a different amount of energy (=heat) from when you burn it in your body. Just try to live on gasoline and you see what I mean. The calorie is an old energy unit defined as the amount of heat (warmth) needed to raise the temperature of 1 gram of water with 1 degree Celsius (or Kelvin). Power is the amount of energy (heat, warmth) used or produced in 1 second–1 watt is the same as 1 joule/second and a metric horsepower is the energy needed to lift 75 kilogram over 1 meter in 1 second. So if I mount the staircase in my home in a little more than 2 seconds I am producing just about 1 HP. A metric HP is the same as 735.5 W. And you can use brandy to get your dishes ‘flambeed’–40 vol% will do.

  8. I read this review, but see nothing about the operating system affecting the cpu over working. So I will just briefly add my experience FYI. Have a very good old Laptop (Gigabyte) with 4gb RAM and 500gb HD. It came with windows 7 back in 2013 and worked quietly and fast. Around 2016 Windows 10 was pestering me to upgrade to the point my Win7 was acting up. I was forced to up grade to Win 10. Well it worked fine and I quickly learn the ropes, but the laptop would scream and over work. Had a pro service it with full clean and some setting adjustments which somewhat helped, but soon it was back to its old self… working non stop and obviously over hearting. I surmised there was nothing wrong with my box as it worked perfect on win7. Finally I switched OS to Linux mint with the help of a friend, and for 5 years its been perfect. No problems with virus and such and it just never seems to ever overheat and screaming the fan at me. Its like I got a brand new Laptop. Cant see myself ever going back to Windows. It boots 4 times faster than windows and all apps are super fast. The only slowdown is with Thunderbird, but I fear a fault with it, rather than Linux.
    Just saying is all. No agenda here to push.

  9. Referring to ‘spinners’ the larger the HDD capacity the more platters inside the HDD, hence more read/write heads. Also, some heat is generated by the churning of the air inside the HDD by the spinning platters, so the higher the rpm of the HDD the more heat is generated


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