Laptop Coolers are not useful because you already have side cooling vents, but no bottom vents

Antec laptop cooler (not actual size)
Antec laptop cooler (not actual size)

What is a laptop cooler?

A laptop cooler is something placed under the laptop to assist in the machine's cooling.

They come in a variety of sizes and types. Laptop sized, notebook sized, even netbook sized, are available. There are also folding, sliding, even passive vs. active. It may also come with additional USB hubs and more.

A laptop cooler is supposed to keep your laptop cooler by dissipating heat from the bottom of the machine, either by conducting some heat away from it, or by circulating air across the bottom of the machine. Advertisement for laptop coolers often cites premature failure of internal components due to heat stress, and you would want to avoid it.

However, a recent New York Times Tech Blog entry (GadgetWise) stated that the only real reason to use such a cooler is for YOUR comfort, NOT the machine's usable life.

Heat transfer happens via three mechanisms: conduction (by touching), convection (circulating via another medium, such as air), or radiation (infra-red waves). So if a laptop cooler works, it has to occur through these methods. And conduction is the most efficient way to transfer heat, THEN convection, THEN radiation. Keep that in mind.

Let us examine how a laptop cooler really works when examined in detail.

Cooling by conduction

In vast majority of modern laptops, the bottom is made of PLASTIC. There are some that is made of aluminum, magnesium, or other metals, but those are few in number.

Plastic is NOT a good heat conductor. In fact, it is generally considered a heat insulator, depending on specific formulation.

Thus, cooling the bottom of a laptop made of plastic is just just barely helpful. It is like trying to cool hot liquid in a plastic cup by putting the ice OUTSIDE instead of inside the cup.

Cooling by convection

Convection is how the "active" coolers are supposed to work: by forcing air across laptop's "hot bottom", to draw away the heat.

Do you see any seams at the bottom of the laptop? No seams at all. There are not supposed to be any seams in the bottom of a laptop any way, right? So the air is not going through the laptop itself. The airflow is simply across the bottom, mostly made of PLASTIC, which does NOT conduct heat. It'd be like trying to cool a plastic cup of hot liquid, not by blowing on the liquid, but blowing on the outside of the plastic cup.

Cooling by radiation

Well, the color black actually absorb heat, but it is at the bottom, so it's not really seeing any light, thus, radiation is not a significant factor in either heating or cooling.

4 views of a Toshiba laptop, note the side vents on the bottom two views.
4 views of a Toshiba laptop, note the side vents on the bottom two views.

How laptop cools itself

If you look at a laptop you will find that it probably draws in air through the gaps between the keys of the keyboard, probably with an internal fan, or via conduction through "heatpipes", and vent the heat through the side vents. My Sony VAIO laptop has this feature, and it is several years old already. So this is hardly new.

Examine your laptop and feel where the hot spots are at the bottom, and where are the heat vents. It is probably not where you think it is.

Ever seen a thermograph?

A thermograph basically is a thermal photo, like those IR cameras shown on Mythbusters or Time Warp (both Discovery Channel programs). What if you apply one to laptop cooler review? Benchmark Reviews did just that.

I don't want to steal their picture, so I suggest you go take a look at their review. (Very nice review, by the way) Go to the "test and results" page, and you'll see a thermograph of before cooler, and after cooler. The hotspot in the middle is reduced SLIGHTLY, and both CPU and HD reported slightly lower temperatures. And that's a premium cooler (MSRP of $70 USD).

Conclusion

Laptop coolers, for most laptops, notebooks, and netbooks, provide much less benefit than you may think, because they simply draw heat from the wrong part of the computer, through barely-heat-conducting plastic.

Laptop designers are not stupid. They know that the bottom of the laptop is usually leaning against a desk, or pillow, or your lap, and they do NOT want heat to go there, since from there it goes nowhere. Notice the "feet" of that Toshiba laptop? The bottom does NOT sit flush to the surface. Most laptops are like that nowadays. They have side vents, which cannot be obstructed easily. And you don't need a laptop cooler to do that.

At $20-100 per pad, and the fan drawing power from the limited onboard battery run-time, AND one more item to carry, a laptop cooler's disadvantages simply outweighs any benefits it may offer. 

If your laptop has clogged vents, or is already overheating often (older laptop, or desktop replacement, which run hotter), then you will likely need a laptop cooler. However, for laptops that are working fine, you probably do not need one.

You can always reduce heat build-up by using power-saver mode on your laptop, which reduces CPU speed, and thus heat build-up.

And if you really need one, get a soft passive pad, like the ThermaPAK HeatShift. Those sit flush to the bottom of the machine, no matter the "feet". HeatShift shows a 9.2 degree drop in average temp in a CNET test. Your results may vary.

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Comments 31 comments

thisisoli profile image

thisisoli 6 years ago from Austin, Texas (From York, England!)

I suggest you try using a laptop cooler such as the ones provided by Zalman, the difference between before and after is highly noticable, especially if you try playing games or similar.

I bought my first cooler after my first real high powered laptop died after the cpu fried, and would definitely suggest that a laptop cooler is an integral part of any high powered laptop setup!


kschang profile image

kschang 6 years ago from San Francisco, CA, USA Author

You sort of missed my point: NOT ALL laptops and notebooks need one. I am sure people have personal anecdotes that supposedly "prove" the need for one, but is that pointing at the inadequate design of the machine and its cooling?

Designing a cooler that cool the bottom where heat does NOT conduct simply makes no sense. A REAL enhancer would have tried to draw additional air from the side vents by accelerating air flow there, but they can't make a generic one to do that, but they can make one for the bottom, and try to convince you that you need it, even if it doesn't exactly do what it *should* do.


Pamela N Red profile image

Pamela N Red 5 years ago from Oklahoma

I don't have a laptop cooler but I do have a lap desk from Brookstone because my MacBook gets really hot and burns my legs.


kschang profile image

kschang 5 years ago from San Francisco, CA, USA Author

But your lapdesk is not a cooler. It's just a pad, right?


Paul P 5 years ago

Hi Kschang,

I've got a lot of experience working with all different types of coolers and different laptops and I can tell you that what you are saying is only true in some cases, but not others. I have found that on my dell laptop with plastic casing that fan based cooling made a huge difference because it accelerated the air through my laptop and provided a space for my laptop to such in air from the bottom. Especially in situations where I was using it in my bed, it was particularly useful and dropped my temperatures significantly. I find the same coolers to be less useful for my envy 15 laptop which gets very, very hot and is made of metal. I think a large heatshift pad would do well for that situation, but everyone seems to indicate that after a enough hours, it's less useful because it can't dissipate the heat fast enough. That being said, it's probably the most effective solution for a few hours.


kschang profile image

kschang 5 years ago from San Francisco, CA, USA Author

@Paul: thanks for the feedback. This is not meant as a universal condemnation of cooling pads. One must always evaluate whether cooling pads actually help.


juncolt profile image

juncolt 5 years ago from saudi arabia

With the information I got from you I probably would cancel my plan to buy a cooling pad for my new netbook. Your hub makes a lot of sense.


Rose Kute 5 years ago

I have a Dell that is about 4 mos old. I just lost my Toshiba Limited Edition this past June, it just crashed on me. I changed the hard drive but it didn't work.

Back to the Dell (my Toshiba was a lot better), running on Windows 7, is overheating.

I don't know how to check to see if its cooling system is working. It heats up so much I have to turn a fan on top of me because the laptop makes me hot.

I also read on your article that the vents might be clogged, I do have dogs and cats that shed a lot. Should I use a can of air??? if so, when puter is off???

today this new symptom started, when I click on a link the computer just stops, it's not freezing but it does not take me to the page UNLESS I keep moving the cursor.

I have had computers for years and never had such problem. Could that be the processor?

thanks


Rose Kute 5 years ago

btw, my Toshiba did not overheat ever.

Is this overheating a Dell thing????

I just read some of the posts above.


Rose 5 years ago

I just posted about my Dell laptop overheating and the post disappeared

it's overheating and now when a click on a link it won't go anywhere unless I keep moving the cursor (not really freezing though)

and it gets so hot I need to turn on a fan on top of me it gets me so hot burning my legs


kschang profile image

kschang 5 years ago from San Francisco, CA, USA Author

@Rose -- due to amount of spam your messages don't appear until I approve them.

Regarding your questions: just turn the laptop over (with it off, of course), and see if the vents are really dirty. You'll know it when you see it. There should be vents to the sides and maybe under as well, but that's rather rare.

Not all freezing and such are heat related. Sometimes you just have to clean it software-wise with CCleaner (free) and uninstall some software that you don't use.


Chris 5 years ago

Several resources can be employed to help keep a notebook cooler. I like monitor the cpu temp and regulate the rpms (increase)on the fan to help keep mine cool. A lot of notebooks do have air intake vents in the bottom. In some designs they are an inlet for air that the cpu fan exhausts out the back vents. Elevating the laptop by means of a cooling pad can help keep the heat sink cleaner by minimizing the dust in air that gets sucked into the intake vents. Dust is a leading cause for laptop overheating. I've take apart a lot of them and the dust is usually clumped up between the heatsink and fan. The heatsink has cooling fins and once they get clogged the cooling ability is drastically reduced.

In some designs covers with vents in the bottom of the laptop help cool components such as memory . Some notebooks are elevated with feet in the bottom base. Others r not. As I mentioned there are benefits to elevating the notebook.


MOE 5 years ago

If plastic doesn't conduct heat, why would the bottom of the laptop be hot... Am I missing something or does physics work differently for me?


kschang profile image

kschang 5 years ago from San Francisco, CA, USA Author

@Moe -- plastic is a BAD heat conductor, but it *does* conduct SOME heat. (Besides, some laptops now are made of metal... Aluminum or magnesium)


Chuck 4 years ago

For me the difference between a good cooler and not having one at all is night and day. If I am feeling a lot of heat on the bottom of my laptop, then obviously there is a lot of heat escaping to the outside of the plastic.

From my own personal experience, playing high graphics games without some sort of cooling on the bottom is almost impossible. For instance, right now my laptop cooler is broken and as the game progresses, mylaptop bottom gets hotter and hotter and the graphics start lagging and eventually breaking down.

To cool it back down, I hold the bottom up to a large oscilating fan, I also still use the broken cooler as a spacer between the pc and a pillow, so it's not smothered in fabric. I cool the metal cooler down as well, since that is hot, obviously there is a lot of heat transfer going on.

The graphic improvement from about 5 seconds of cooling is instantaneous.

I do, however, notice on my Dell, that the inlet for the air into the built in fan, seems to be on the bottom, while the outlet is on the left side of the laptop. Horrible place if you ask me, because it's just sucking up the heat the laptop is creating.

I'm thinking of new ways to keep my laptop cool. I've considered venting the fan directly into the crevice between my laptop and broken fan, even trying to transfer cold from a drink cooler.

So I have a question for you...my drink cooler/heater seems to have some type of heat sink/exchanger looking thing, and then a fan on the side. Is there anyway to use that exchanger safely on a laptop? Any ideas?


kschang profile image

kschang 4 years ago from San Francisco, CA, USA Author

@Chuck -- I'm guessing your drink cooler uses the Peltier effect

http://en.wikipedia.org/wiki/Thermoelectric_coolin...

However, there's no "good" way to directly transfer this cooling effect to your laptop. If you cool below ambient temp, you get condensation problem (and we all know what happens to wet electronics) ;) You may be able to use a "heatpipe" but that's not as easy as it sounds. Simplest is use air (convection) by blowing cool air into the laptop, but that would depend on how your current airflow is structured.

It may be easier to simply fix the fan by opening the laptop. There's gotta be some Youtube video on this. :)


allan 4 years ago

i have a few different laptops. i use a £20 cooling stand. without it my higher end laptop reaches 80c just on my lap or a pillow, however the cooler fan itself doesn't help... why would it theres fans inside the laptop. just by having that space between surface and base its reduced to 40 - 50c. im wondering now if a cooling gel pad will help at all, what do you think?


Nathan 4 years ago

I completely disagree with this.

A simple core temp reading will show about 9-10 degree difference while using a cooling pad.

For someone gaming or power computing for long periods of time this can be the difference between permanently damaging the system or not.


Jorge 4 years ago

Perhaps the author hasn't tried running a high power laptop running with a game or a simulation for 90% CPU consumption. Many laptops become so hot that you can no longer stand having them in your lap.

usually laptops that are designed with more "look cool" factor than perforamnce in mind (e.g. apple or sony) are the ones that probably don't benefit from coolers. All the rest that have little slots in the bottom and draw air from the bottom to the sides, get a huge benefit from laptop coolers.


kschang profile image

kschang 4 years ago from San Francisco, CA, USA Author

I run a 17 inch Toshiba with Intel Core i7 quadcore. :)


Dennis 4 years ago

Well, my Dell laptop has intakes on the bottom and exhausts on the side. If there was a cooler below, it would cool the air going into the computer, right? So that would help. Worst thing is to put it on your lap, a pillow, or anything soft, as that will likely close up the intake vents on the bottom.


kschang profile image

kschang 4 years ago from San Francisco, CA, USA Author

Just make sure your cooler blows the right way. :D But remember laws of thermodynamics: conduction better than convection better than radiation. Coolers use convection. Passive coolers like thermo pads use conduction.


billybob 3 years ago

Actually, convection is almost always a more effective way to transfer heat. That's why engineers put fans inside of computers next to the hot CPU. That's also why convection ovens cook food, so much faster than traditional ovens. Putting a small fan next to your computer is much more effective than a 'cooling pad,' unless the pad is being constantly cooled or refrigerated below ambient temperature.


kschang profile image

kschang 3 years ago from San Francisco, CA, USA Author

Conduction is better for moving heat, but convection is easier to implement cheaply. It's like difference between a hibachi and a barbeque.

Heatsink is attached to the chip via direct contact, thus, conduction. Fancier setups use heatpipe, which is sorta between conduction and convection. From there it's radiation or convection into ambient air.

So... yes, air near the vent would help to make sure "ambient" is really ambient.


Cash 3 years ago

I'm sorry, but the OP is completely ignorant. Most modern laptops have vents on the bottom to help cool the computer. If you were writing this article about just SOME laptops then maybe it should not be titled "Laptop Coolers are not useful because you already have side cooling vents, but no bottom vents."

You should have used a title that would actually correspond with what you're talking about. Like, "Why a cooling pad MAY be useless for your laptop." Still hooks the reader in, and you avoid sounding like a complete and utter idiot that has been living under a rock. They wouldn't make these products, and people wouldn't buy them if there wasn't a valid use for them.


kschang profile image

kschang 3 years ago from San Francisco, CA, USA Author

The point is blowing air against warm plastic to cool what's on the other side is about as efficient is trying to cool your coffee by blowing ambient air on the OUTSIDE of your coffee cup, which was what I said.

If they *really* want to make cooling efficient they would have made the entire bottom out of metal to conduct heat away from the innards, then figure some other way to pipe the heat out. But then you'd never be able to put it in your lap as it *does* burn.

Perhaps the title and the conclusion was not as "clean" as I'd like (it was written several years ago) and perhaps cooling pads is the best of a bunch of lousy solutions, but the point stands: you don't cool a laptop by blowing air on the side that's NOT hot. It's just not efficient.


logan 3 years ago

your wrong my laptop notebook has serveral slots in the bottom of it including 1 with a fan in it but i aslo bot a cooling pat and it worked with a crap so a replaced it with a window fan you know 1 that you would put in a window and it keeps my laptop at 40-50 and the cooling pad kept it at 80-90 and that cooling part reading is without cpu usage and the window fan is with minecraft with far render


Egg_of_Columbus 2 years ago

I think you will find that, in most cases, the problem of no bottom air vents can be solved within a couple of minutes, as long as you've got a Phillips screwdriver.


H-man 2 years ago

Kschang. Um. Did you do ANY tests to confirm your hypothesis? I have a 17 inch Sony Vaio made of plastic with 4 vents at the bottom. It started slowing down and turning off. I ran diagnostics, saw the temps were thru the roof (glad it didn't blow) so I took it apart and cleaned up the fan and vents which weren't too bad. Didn't help much. Got a cheap Dell cooler stand and it runs quite a bit cooler by measurement and runs better. I agreed that a forced air system added to the side might be better.


Naveed Ahmed 624 profile image

Naveed Ahmed 624 17 months ago from Pakistan

A laptop cooler or a cooling pad really helps. I bought one a couple of months ago, and have noticed improvement in the performance and heat ventilation of my laptop. Therefore, you cannot say that laptop coolers do not help. They help a great deal, because laptops blow heat from the bottom too, which is obstructed by hard mediums like our laps and desk etc. A cooling pad has a design to allow heat conduction through the air, which really helps in cooling them. So, in my opinion and observation, there is no harm in using Laptop cooling pads.


Shivam 13 months ago

I am purchasing a new laptop

One has seams at the bottom(lenovo)

The other doesnt, its completely shut(HP)

Which one should i go for?

I intend to run a few games in it

Like FIFA and others

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