Heat is the enemy for many electronics, but especially for modern PCs. They're complex beasts with many parts, and excessive heat in just one area can cause a computer to crash, assuming a component doesn't fail permanently. It's almost a miracle that PCs run at all, given how many apps are designed to push their performance to the limit. You can thank decades of work by engineers for getting us to a point of stability.
Paying attention to ambient conditions
Ventilation is king
In a home with central air conditioning, ambient heat isn't usually much of an issue, as long as the thermostat isn't set far above room temperature (which is about 68-72F, or 20-22C). Not everyone lives in a place with central air, however, in which event some rooms can potentially be much warmer than others. If you're not paying attention, ambient conditions will compound what your PC is enduring under high-intensity workloads.
The most important thing is controlling ventilation. Air should not only flow properly out of your computer, but over and around it, at least as much as you can enable. If you've got a laptop, putting it on a stand will let air flow underneath, which is especially important if any vents are located there. Tower PCs should be kept out in the open rather than stuffed in a cabinet. Placing a tower on your desk is also generally better than under, space permitting.
Air should not only flow properly out of your computer, but over and around it, at least as much as you can enable.
Think about sunlight as well. If a room is bathed in sun most of the day, its temperature is going to rise, and your PC might also absorb some of that heat directly. You may need to get in the habit of closing blinds or curtains for a few hours.
If conditions seem sketchy despite making these passive changes, that's when you might need to break out a fan, or even a window-mounted AC unit. In extreme scenarios, it could be time to move your computer setup to another room.
Reapplying thermal paste
Only as necessary, and very carefully
Thermal paste helps a CPU's heat sink work at maximum efficiency by eliminating air pockets. If you've only ever used pre-built PCs, its existence may be news to you -- when a desktop's operating properly, the initial paste application may last all the way until you upgrade, without incident. In laptops, meanwhile, it's often incredibly difficult to reach the CPU in the first place, and battery life may become a problem before heat does.
Consider reapplying paste every three to five years, and possibly sooner if internal temperatures are regularly topping 80C (176F).
You should consider reapplying paste every three to five years, however, and possibly sooner if internal temperatures are regularly topping 80C (176F). The process for desktop PCs involves unplugging your computer, detaching the CPU cooler from your motherboard, then using a microfiber cloth moistened with 90% isopropyl alcohol to clean both the CPU and the cooler. Once everything is dry, you can apply a pea-sized dot of thermal paste to the cooler and reinstall everything.
Try to rule out other overheating causes first. While reapplying paste isn't overly complicated, there's still the risk of misapplying it, not to mention static discharge if you're not grounded. Also, the step below is more likely to make a difference.
Cleaning out internal and external dust
You'll be surprised at the build-up
Even in a well-ventilated room, dust will inevitably accumulate around a PC's fan vents. The process is slow, but begins the moment you unbox it. After several months, it should be plainly visible. After a year or more, it'll be disgusting. And the more that gathers, the harder your PC's cooling system has to work just to maintain the status quo.
The more dust that gathers, the harder your PC's cooling system has to work just to maintain the status quo.
It's easy to deal with this contamination. Every month or two, clean the vents with a microfiber cloth, compressed air, or some tissue paper. Just remember that if you're using compressed air, the can should stay level, since tilting it too far up or down may spray fluid.
Desktop PCs should be opened up at least once per year for internal cleaning. You might be surprised at how much this can lower temperatures -- the reason being that if enough dust settles, it can form an insulating layer, trapping the heat produced by your CPU and GPU. Be extremely cautious when you're rummaging around, though. Unplug your PC first, and avoid using any cleaning methods that could leave liquid or debris on the circuitry.
Being careful with overclocking and other PC settings
Don't forget to take a break sometimes, too
Higher clock speeds on a processor mean faster performance, so a variety of first- and third-party software tools exist to boost stock settings. Normally, overclocking isn't a big deal -- gamers do it to eke out the best possible framerates, and non-gamers may do it to stretch out the usefulness of an older machine. The issue is that if you push things too far, your PC can become unstable, and the increased heat may shorten the lifespan of some components.
As a rule of thumb, you should be safe with first-party utilities, i.e. the ones made for your PC and/or video card. Nevertheless, it's wise to keep an eye on internal temperatures using apps like the Windows Task Manager or HWiNFO. Anything below that 80C/176F threshold I mentioned earlier is typically fine. Short spikes above 80C may be acceptable, say if you're playing a game with photorealistic 3D -- if that heat is prolonged, though, it's time to disable overclocking or invest in a better cooling system. Gamers with high-end Nvidia GPUs frequently invest in all-in-one (AIO) coolers that combine large fans with a liquid pump.
Short spikes above 80C may be acceptable -- if that heat is prolonged, though, it's time to disable overclocking or invest in a better cooling system.
Note that in Windows 11's Settings > System > Power & battery menu, you can adjust Power Modes to favor performance, power consumption, or a balance of the two. You may be able to bring heat under control simply by dialing things back from the Best Performance mode, but that shouldn't be necessary. It's usually purpose-built overclocking features that push things into the danger zone.
It's important to ease the load on your PC when you can. Avoid running unnecessary background apps, something you can fix by going to Settings > Apps > Startup. And if you do play a lot of 3D games, take a break every hour or two -- that'll give heat a better chance to dissipate.