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Comment by coldtea | Hacker News Reader

>One of the things that really drives me nuts is my computer’s fan turning on when I know really shouldn’t be. I have lived and worked with people for whom having their fan randomly turn on for no reason is completely normal, and I just can’t understand how they can bear it.

Yeah, but try standing in their shoes: they too are probably wondering how you can bear getting worked up over such small things such as fans going off.

It admittedly sounds like a worse situation to be in (seeing that it means living one's whole life in constant irritation) than to have noisy fans.

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>getting worked up over such small things such as fans going off

Fans spinning up is an indicator of something. Usually an indicator that the machine is under heavy load and you need to watch out for the things that come with machines under heavy load: slower performance, overheating, graphical artifacts, potential crashing, etc.

If my fans spun up when I was not aware my computer was under heavy load, I would believe something was wrong with my computer. If I spent any amount of time researching why my computer was under heavy load and my conclusion was that it was not under heavy load and that the fans just spun up for no reason, I think I'd be rightfully irritated.

Imagine a doorbell that rings randomly even if no one is at the door. In the grand scheme of things it's minor. But it shouldn't be happening, and every time it does I have to get up and walk to the window to see if someone is actually there. Every time the doorbell rings and no one is there, I'm going to get more and more irritated.

If your machine crashes, overheats, or has graphical artifacts at 100% load, it's broken and you should fix it.

If your machine spins up its fans for no discernible reason throughout the day, it's broken and you should fix it.

It’s not. Using the cpu is a supported feature of normal computers.

If you can say "the fans are spinning up because this piece of software is using the CPU more" then it's not "no discernible reason".

> no discernible reason

What if the "no discernible reason" is just poorly coded software?

Then the PC and the OS is off the hook and the search continues with the software.

That's the definition of a discernible reason. If the CPU is being used hard enough to need more cooling, then the question is answered.

That's too limited a view at the issue. Why is the CPU running that hard? If the user is not doing anything CPU-intensive, yet the fans spin up, clearly the CPU is hot, but why? What is it doing?

Most people will categorize crashing, overheating, and graphical artifacts as a more severe problem than "what's that small noise I hear once in a while".

It surely is an indicator of something but if you have a modern laptop with factory configuration from one of the generic Windows laptop manufacturers, chances are it's an indicator that the power settings are set up for marketing/benchmarks and not real world use. Every single ultrabook and workstation laptop I've had outside of Apple products have been poorly configured, especially the Intel Turbo Boost settings.

I'm not an expert in CPU thermals by any means, but from what I've gathered, in order to eek out a tenth of a gigahertz for their marketing materials (with rapidly diminishing returns because physics), manufacturers usually set Turbo Boost Power Limits 5-10 (or more) watts too high. Since Turbo Boost usually maximizes a single core's frequency and the heat generated increases exponentially, it creates a very concentrated heat spike in the silicon. Even if the CPU heat sink is good enough to passively dissipate that much heat from all of the cores, the turbo boost hot spot forces the fans to spin up early before the CPU knows how long the boost will be needed (otherwise Turbo boost would significantly reduce the lifetime of the CPU). Combined with random scheduled OS tasks that take a split second of turbo to run a process and firmware configured with a minimum fan running time to avoid even more annoying pulsing, these power limits cause many mass market laptops to needlessly spin up their fans all the time.

It's ridiculous but I've been running ThrottleStop/the equivalent on Linux to under-clock every laptop I've owned since Turbo Boost was introduced. A small 10-20% reduction in turbo boost power limits is rarely noticeable unless you have a very specialized and irregular CPU-bound workload but it makes a significant change in the amount of heat it generates and gives the passive dissipation enough time to absorb a boosted workload instead of spinning up the fans in an emergency.

> if you have a modern laptop with factory configuration from one of the generic Windows laptop manufacturers

The general advice is to never ever leave the factory configuration in place (if you're not going to install Linux at least reinstall windows)

Hardware manufactures are, in general, not your friends.

Turbo Boost power limits have to be changed using the Intel Tuning utility or a similar piece of software that sets the correct registers. Operating systems usually leave those lower level details to the BIOS so installing a new operating system won't do anything unless the system default is set correctly and some bloatware driver is updating it at boot. Usually the manufacturer does it in the BIOS so you have to overwrite it every time you boot; or they do it at the factory, in which case just setting the registers once will be enough (I believe they're nonvolatile?)

I suspect it's partly a sensory (-integration) issue.

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