How Cold Is Too Cold? How Hot Is Too Hot? (Computer Hardware)

General rule of thumb for all PCs: The colder it is, the better it runs. Some jokingly say that a computer runs best with a "frosty dew" on it. The reason that’s a joke is because condensation in any form that’s physically on the motherboard (aside from cooler units) is obviously bad, because water and electricity don’t mix.

General rule of thumb for computer monitors (all types): Operates best at room temperature (72 F/22.2 C) while not in direct sunlight.

General rule of thumb for laptops (all types): Typically you will find at least one "spot" on a laptop that’s warmer than the rest of the unit after it’s been running for a while. It differs in location dependent on model, and the spot that gets hottest is usually where the processor is. Your best defense against laptop overheating is to ensure the fan is clean. Spraying dust removal spray lightly on the fan while the laptop is OFF (obviously) is usually the only way to clean it. If the vent slots are thick enough you can also use a cotton swab (laptop has to be off for that also).

How to deal with extreme temperature situations

Cold (computer): If any computer is in a very cold environment and has developed a frost on it, wipe what you can off the case, DO NOT turn the unit on and let it sit for a good 20 or 30 minutes to let the case adjust to room temperature before powering it on.

Cold (laptop): If a laptop is cold enough, the keyboard may start to curl (literally) at the corners and the touchpad won’t work at all because the sensor just won’t operate at that temperature. You need to let the unit warm up to room temperature first in the off state before powering up, else you risk damaging components. In addition you may notice it’s difficult to open due to the cold "flexing" the hinges. If when you start to open the laptop lid you hear cracking/rubbing noises, STOP. Close the lid and wait for the hinges to "flex back" before opening again.

Cold (CRT monitor): Unless there’s frost on it, a CRT can usually be powered up even in the coldest of temperatures. The screen will show a very dim picture until the tube warms up.

Cold (LCD monitor): LCD monitors are usually very forgiving when it comes to cold. However with frost on it you should let it adjust to room temperature first before powering it on to avoid condensation damage. You will also notice a dim picture on startup because the backlight bulbs haven’t quite warmed up just yet.

Heat (computer): In an extreme heat situation you can open the case to "air it out" first for about 10 minutes, then close the case up and start the computer. IMPORTANT NOTE: Running a case open does not cool it better because the air flow from the fans is wrecked at that point. You need that case closed so the air gets to where it needs to be. If the computer still runs too hot, you need better fans and/or a case that has better air flow and/or the addition of a cooling system.

Heat (laptop): Same situation as a desktop PC. Open the lid, let it sit and adjust to room temperature first before turning it on. You will know it’s ready to turn on if you touch the LCD screen and it doesn’t feel hot to the hand. Otherwise, wait until it cools off. It will usually cool off quickly.

Heat (CRT monitor): Ordinarily there is no danger in starting a CRT monitor even if it’s been "cooked" a bit from extreme heat. However if the enclosure holding the tube feels hot, you should wait until it cools down first before turning it on.

Heat (LCD monitor): LCD screens will run even in the most extreme heat because they don’t produce that much heat to begin with. What to watch out for is the warping of the screen enclosure. But this is rare and basically never happens unless the environment is so hot that is starts to warp molded plastic.

I’ll put it to you this way: If you’re in an environment hot enough to warp plastic, you shouldn’t even be there let alone a computer.

"Warning Level" temperatures:

Ambient temperature below 35 F/1.7 C: Generally speaking it’s too cold to operate at this point. You’re dangerously close to freezing and that’s when the physical properties of computer hardware change by flexing (usually). Not a good idea to operate a computer below this mark.

Ambient temperature above 90 F / 32.2 C: It would be rare to operate in this temperature because you’d be sweating profusely just sitting there, but some do. Your monitors and peripherals will run fine but the computer starts acting like an oven. Any air going thru there is also warm (or possibly hot) which at that point doesn’t help very much to cool it down.

Final notes

There will be those that vehemently disagree with me as to what’s too hot/cold for computer operating temperatures because I haven’t taken into account other factors such as altitude and humidity. And yes I know those both count in a big way. If you want to add commentary specifically concentrating on altitude/humidity, be my guest.

Temperature is very easy to dismiss because most of us don’t think about it when it comes to computers. We just assume it doesn’t matter when it fact it does. As long as you know when and when not to operate a computer based on temperature, you should be a-okay.

Also, bear in mind all computer hardware and laptops have specifications that state minimum and maximum operating temperatures – and they’re usually 100% accurate.


  1. how hot should the inside of the computer be? my case LCD temp display, any temp it should be below?

  2. As long as the air coming out of an idle computer is just barely warmer than ambient, you should be fine. It’s the CPU and HDD temps you should be paying attention to. Download CPU Fan to check those.

    I diagree with one part of this article. Running a computer with the case open definitely improves temperatures across the board. A lot of overclockers do this. Most heatsink+fan options have the fan blowing into the CPU. With a closed case, outside air HAS to come from an intake fan, side or front. With an open case, outside air is ambient.

    It’s worth mentioning that after some particularly extreme computing – maybe gaming or compressing a particularly large file – one can prolong hardware life by having the computer idle for a while so that the CPU gets down to its idle temperature. There are fan controllers out there that have the fans run for a few minutes after the computer had been shut down…same thing, just slightly more effective and more expensive (thought the electricity bill savings might make up for that).

  3. I have no idea why I said “CPU Fan”. It’s called “Speedfan”. Oops.

  4. Gustavo Fco. says:

    Than you very much for your information, since I live in a rather hot place I wanted to know when to turn the air condition on in order not to have trouble with my PC.
    Anyway thanks again for your kind info.

  5. Working in ALL aspects of data processing since 1972 you can imagine that I’ve heard the ‘how hot is too hot’ question a few times. The best answer I’ve been able to come up with is the following little axiom, with one qualification: Given that the cooling system in use is functioning properly for the design of the computer and location, if it’s comfortable for you, it’s comfortable for the computer. One more thing, being in Alaska, we have to watch for saturated cold. Sometimes, even an hour at room temperature is not safe. Once when a notebook had been ‘saturated’ at about 20 below, I waited till it felt to be about room temp. The drive would not spin up. A screwdriver and an I/R probe later, the drive was still about minus 5 degrees. And this after more than 30 minutes. Did you know it gets over 100 degrees in Fairbanks in the summer?

  6. My air conditioner is broken. The room my computer is in is about 95 degrees F, and will likely stay that way for a few days. Will my computer be okay if it’s turned off? It’s burning hot to the touch when I open up the case…

  7. What if your computer is left in your car on hot days? Does the computer being in a black case make a difference for that also?
    When I turn my computer on it says running file check for C: (or something of the sort), and never really goes anywhere no matter how long I wait.

    I am wondering if the problems I am having with my computer are from leaving it in my car on very hot days?
    Any help you can give me on the matter would be much appreciated. Thank you.

  8. i have a pretty good computer (desktop) with a Phenom II x4 940 w/ the CPU fan that comes in the box… and my computer was running a 124F im not sure if this is bad or what but it is alot hotter then my old CPU. you dont have to

  9. Madjordainian says:

    I have been running an old gateway 2000 system which is stored outside under an “out house” looking structure sitting on a deck since september of 2006. It is out there 24/7 364.25 days a year not powered up or even plugged in unless I am out there using it in my observatory. I have powered it up from a “cold” start in temperatures from 100 F to -10 F without any problems and proceded to have it run all through the night running my various camera, tracking, & star charting applications without a hitch. Yes there were a couple of times on a spring or fall evening when the humidity & dew points had caused some condensation in the monitor screen, but after a few minutes warm up of the screen it was gone with no ill effects.

    This is an old system Duron 1Ghz 133 fsb, & RAM running on a winxp home OS with 4 80mm cooling fans 2 to each end of the case. Only the power supply was upgraded to a 350W from the stock 240W and of course an addition of 1.5 gig of RAM, (takes a little more power than 240W to run several USB cameras) Maybe it's just this box, but it seems a heck of a lot more durable than would be first expected, that's why such an old system……… It was a throw – away so no big loss if it didn't last long, but due to needing a little more speed with larger image files of some of my newer equipment this old war horse will be getting replaced this summer with the next generation of “obsolete” computer I have sitting around. An AthlonXP 2500 on a 333mhz FBS based system…….It too will be out there for the duration, we'll see how it holds up under the same conditions. Why not a more current notebook system, temperature thermocliens between coming in from outside almost always resulted in a frosted system when bring it back in from the cold, even leaving it running cetain parts were still cold enough to frost. Way too slow of a startup & screen warm up on those cold days if left out with the equipment.

    you can see the setup here: <…>

  10. Should i leave it running like cars or wait until i am at home in the afternoonTim

Speak Your Mind