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Being an active laptop user I often wonder if they were designed so they are not capable to manage it's heat when they have 100 % GPU and CPU load during long time (say 2-4 hours)?

There are a lot of tweaks aimed to address this issue like improved thermal paste and even hardware augmentation and laptop cooling pads. So there is a big industry that takes money addressing this problem, that shows the problem is quite widespread. However I also heard an opinion saying that a laptop doesn't need anything fancy to work properly. You only should clean its cooling system sometimes, and normally a brand new laptop should not suffer from overheating (and if it does, the laptop has cooling/hardware issues and is eligible for free support repairing or refund)

I couldn't find any reference or warranty terms covering this, and being an active consumer of laptop industry for more than decade, I still don't have any idea if laptops are designed so they are not able to work at full power and need to throttle or it should not commonly happen if everything is ok with it.

P.S. Any (semi) official manufacturers input here is embraced

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    they're designed to be as cheap as possible, so more people will buy them. Throttling is so much easier than building a thermally efficient case & airflow that no-one is willing to pay for the improvement. – Tetsujin Apr 22 '19 at 11:25
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    @Tetsujin is it your assumption or you are saying this on behalf of a laptop manufacturer? – The Dreams Wind Apr 22 '19 at 13:27
  • "if laptops are designed so they are not able to work at full power" - this is something only manufacturers know, and probably not willing to share. Definitely majority of laptop users don't often use laptop at full power for an extended period, maybe it's only considered during development of high end gaming laptops. – Máté Juhász Apr 22 '19 at 13:32
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    If you want to know whether a laptop can deliver top performance for extended periods of time, read reviews! They test this kind of stuff. Non-workstation laptops can commonly only work at peak load for a few minutes at best. – Daniel B Apr 23 '19 at 11:34
  • @DanielB my 7 years old HP laptop succeeds to work up to an hour under stress test without getting throttled, but only if I run it right after cooling system cleaning. Of course laptops are more exposed to overheating as they have less airflow and miserable amount of dust inside makes cooling way less effective, but I wonder if manufacturers actually ensure their laptops should work at peak load for reasonable amount of time. (Of course they would check it without taking countless factors into account) – The Dreams Wind Apr 23 '19 at 11:50
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Yes, laptops and desktops are designed to throttle on several computational aspects:

  • Thermal throttling :
    Reduce CPU speed due to heat, which is why all modern CPUs and motherboards incorporate abundant thermal sensors, with matching support in the operating system. This behavior can be modified by settings in the operating system by controlling fans speed, but a modern CPU will also regulate itself.

  • Power limit throttling :
    This is limiting CPU speed to its rated Thermal design power (TDP). This is the maximum amount of heat generated by a computer chip or component that the cooling system in the computer is designed to dissipate under any workload. This is usually preset by the manufacturer (and usually quite conservatively) and computed for when running what the manufacturer considers are "real applications". This can usually be modified by applications from the manufacturer.

  • CPU throttling or Dynamic frequency scaling :
    This is adjusting the frequency of the CPU automatically "on the fly" depending on the actual needs. This is partly done algorithmically and automatically by the firmware burnt into the CPU controller and cannot be modified, and also partly done by modifiable operating system settings.

For your question:

if laptops are designed so they are not able to work at full power and need to throttle or it should not commonly happen if everything is ok

This heavily depends on the design of the computer.

For example, Thermal throttling can be avoided by good enough cooling systems, which are usually optional on high-end computers or can be added by knowledgeable users.

Power throttling can be avoided by the motherboard supplying enough power to have all cores running at maximum speed. The usual case is that in order to put some cores into Turbo Boost, power needs to be reduced to the other cores.

Dynamic frequency scaling can be modified by overclocking the CPU using specialized applications, sometimes supplied by the manufacturer.

One well-known application in this area is the free ThrottleStop, described as "a small application designed to monitor for and correct the three main types of CPU throttling that are being used on many laptop computers", but which can do many other adjustments (including defining the limits of throttling, both up and down).

For more information about ThrottleStop, see the article
How to Lower Temperatures, Stop Throttling, and Increase Battery Life: The ThrottleStop Guide (2017).

For Intel CPUs, Intel also supplies a tuning and monitoring utility, Intel® Extreme Tuning Utility (Intel® XTU), described as : "Intel XTU is a Windows-based performance-tuning software that enables novice and experienced enthusiasts to overclock, monitor, and stress a system".

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  • 'This heavily depends on the design of the computer'. Does it essentially mean that thermal throttling on such PC means hardware (cooling) malfunction? How do we know if a laptop was designed to stay stable at the full power and malfunctioned or it's just wasn't designed for it and for this reason keeps throttling – The Dreams Wind Jun 27 '19 at 11:53
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    Thermal throttling means the cooling mechanisms are insufficient, which why heavy gamers may need to improve it by various means. A good indication for effective cooling when comparing laptops is to compare their respective Thermal design power (TDP), which is usually known and published. For the CPU or GPU, this will give the maximum amount of heat that the cooling system is designed to dissipate under any workload, so the higher it is the better is the cooling system. – harrymc Jun 27 '19 at 13:37
  • PassMark gives info for finding how efficient the cooling needs to be, as insufficient cooling will cause thermal throttling to cut in sooner. You can find more interesting data on AnandTech and on Laptop Mag. – harrymc Jun 27 '19 at 13:37
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Yes.

Most modern CPUs are designed to throttle to protect them from overheating. Laptop CPU SKUs are usually clocked lower than the identical desktop chip to allow for better battery life and lower cooling requirements.

Your question is more about thermal management in any given form factor. The trend has been towards making laptops lighter and smaller. For example; all 2018 Apple laptops are not capable of using their full CPU power. The cases are too small and sometimes have no fans at all. That's a design choice.

There are other laptops that have adequate cooling and have desktop CPUs inside! So it's really up to the consumer to do research and decide where they want the balance to be: small/light/slower VS. large/heavy/faster

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  • I'd rather say "most modern CPUs". There are some specialized RISC CPUs that actually burn when you overload them. Their advantage is relative simplicity and less use of silicon so they actually emit lest heat and are more effective in terms computing power to electric power ratio so you get more computing power out of 1 kW and 1 sq. m. You need however to plan carefully your workload and optimize code for processor heating. Once you make a bug = CPU can burn. The world is circling, is not it? – Pawel Debski Jun 26 '19 at 19:20
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    HCF (Halt and Catch Fire) en.wikipedia.org/wiki/Halt_and_Catch_Fire – HackSlash Jun 26 '19 at 21:49

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