FP2 GPU gets too hot

And had to find the minimum speed settings that allow for smooth browsing operation while reducing battery heat. Putting 2 cores at 300 MHz did it, easily knocking off about 5 Celsius.


I think this was a bit time consuming as having to run several tests by using the phone in different situations always tweaking those settings.
You have catched your reward for this effort as it sounds.

What have you experienced (if possible in this way), rather reduce clock speed or switch off cores?
Does it mean reducing a cores clock speed to 0 is actually switching off the core or is this done a different way?

Switching off is not always the best solution as e.g. MXPlayer utilizes all available cores.

I am a bit curious about how this multi core mechanism works. Some day maybe I have spare time to get deeper into this multi core matter.

Doesn´t sound much, but in electronic concerns this is noticeable and specifically when it comes to feeling the difference.


My experience with the Fairphone 2 is that shutting down cores, although possible, was messing with Qualcomm’s proprietary mpdecision, breaking hotplugging (dynamic core shutdown) until next reboot. And hotplugging seems to be quite effective in reducing CPU energy use. Changing governor had similar effects. So the least aggressive change that was still very effective was to cap CPU speed. Maximum speed is 100%, and 0% represents 300 MHz, the minimum possible without hotplugging. So I set cores 1 and 2 to “0%”, core 3 to 50% and core 0 to 80%, what seemed to be the best compromise since core 0 normally takes care of the main tasks while core 3 is usually active when there’s user/phone interaction. 80% and 50% was just enough to have smooth touchscreen operation under low stress.

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Concerning the temperature, keep in mind that battery operation temperature ideally should remain below 40 Celsius, and I believe that the phone will shutdown when battery temperature gets close to 50 Celsius to avoid fire hazards. It means that the “overheating” range is only 10 degrees Celsius, so knocking off 5 Celsius gets you half the way out of trouble! Besides, long-term battery life and rate of discharge are negatively affected by overheating. So again, 5 Celsius can pay you handsomely in terms of protecting your battery and hardware.

The question is: if this is so beneficial, why is it that engineers don’t introduce more strict battery temperature control in their smartphone designs? The reason is simple and quite twisted: because users would think those correctly designed smartphones are inferior products, after all they slow down when battery is under stress. The marketing decision therefore is to allow battery and hardware abuse to give users the impression that their gear performs better than their competitors’.

We’re all the way back to the OP question: why smartphones produce so much heat? Well, they overheat by design, it’s another case of race to the bottom, enabled by consumers’ lack of discernment.


Interesting read btw. Active drain will vary from user to user, even with the same device!
That´s a true statement which for some reason don´t have the power to convince many users.

I would guess there is some kind of feedback signal to let mpdecision know and keep track of which core is active and which not. Taking actions in this concern from the outside may cause this routine to break until it´s restarted at next boot.

A few days ago I have tried out the system monitor app to have a bit more insight in background processes. And yes, I realized that core 0 and 3 were the most in use while core 1+2 only occasionally. At first glance your setup makes sense.
I would had expected the core usage to be a bit more balanced for a more even wear. At least that´s the impression I have when on plain Linux.

Yes, indeed.

Another good point from a different view. Not to mention better sells as the hardware lifetime will be limited due to the stress - mainly spent non-replaceable batteries.

Although performance can be measured not every user is out for gflops,gmips and such. So at last my personal user experience would make the decision if a device suits my expectations or not. FP2 is my first smartphone. I don´t have any comparison to others (yet). But up to now I can proudly say - it is a very satisfying start-off.
If it´s not for gaming I think most handsets these days are way to powerful already. To assure a high efficiency there is a good task scheduler and governor needed. Up to now I had assumed this would only be done by Android. But that Qualcomm also had its fingers in wasn´t known to me.

Yes, again as so many things that can be taken influence in by consumers.


Here some pictures showing the difference between battery use under maximum load and when underclocked. First two pictures show clock frequencies and electric current under maximum load, while the last two pictures show clock frequencies and electric current when underclocked. As you can see there’s a reduction in current of about 20%, quite significant. The effect on heat production of such a reduction is clear, keeping in mind that heat tends to increase nonlinearly as energy consumption increases, so reductions close to the limits of the equipment can be quite effective.


Yes indeed, very obvious.
I always say these are the last but most important remaining 5% of work to be done prior to finish.
I am afraid most manufacturers won´t even bother with such optimization issues. At last it´s energy and money which the user has to pay. And if more stress to the hardware results in a shorter lifetime but higher sales it seems to be fine for them.
This market is still mainly untouched related to efficiency.
We have efficiency labels (A+++ - G), although they are not very close to real measurements. But since the EU has released the regulations for the maximum power use of e.g. vacuum cleaners, manufacturers did put more focus on more efficiency by producing better motors, develop better air stream systems and floor nozzles to get a better cleaning after all.

I think it´s time to put this mobile sector also more into regulations.
In the beginning in the 90s most people were concerned about being exposed to the radiation of such devices. Now we have very little values and these are also often test criteria beside others these days.
But if it comes to energy values there only seem to be the batteries capacity and runtime of importance. How efficient the device operates does not (yet) seem to be of any importance. If the runtime is too short usually it´s put that the batteries capacity is insufficient.
I think this is the wrong focus considering there are more mobiles around than humans living. Even notebooks have a much stronger focus on efficiency and runtime no matter which manufacturer.

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Indeed. The problem is that the business model of the GAFA, as they captured and monetized the infrastructure of the Web, is incompatible with engineered efficiency, it runs around keeping your gear as awake as possible so it tracks and spies on you, and then they sell all the information gathered in the most insidious way as an edge factor to the highest bidders. And to think that in the 90s and 00s some pundits were pushing this madness as “free lunch for all.” Well, there’s no such a thing as a free lunch, and I wonder when is it that the average consumer will wake up to realize that they’re being scammed.

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Concerning the flow diagram above for battery heat control, I realized that when the phone is under heavy workload the commands to change speed may fail to update the CPU state. So I created a new version that will check if the new state has been correctly written. I also introduced an underclock exception rule for when GPS is in use, since it’s a critical activity that needs full power from the battery and CPU, easy to be automatized. I’m currently testing the new version and will publish it once I have enough evidence that it’s stable.

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Hi all, sorry for disturbing Dr Cool´s and Patrick´s discussion, but I want to share my overheating problems with new FP2.
I have new FP2 for 3 weeks and stayed with Google Android. The problem I have with overheating is when I am using Waze navigation app car. The situation is:

  • GPS on,
  • Two SIM cards in, one with data on
  • bluetooth on and connected
  • Waze app running
  • USB charing.
    When I am using car air conditioning to cool the the GPU (phone is just in front of the AC exhaust), then it is ok and I can easily go for 2 hours drive. But when the phone is not cooled, automaticly reboot after few minutes, due to the overheating…

Any suggestions for help? Well, my old FP1 (with android w/o google and HereWeGo app, other settings same) has no problem with similar situation. It´s also overheated, but not to the situation of automatical reboot…

Your setup will for sure produce huge amounts of heat, and this is normal, but your phone shouldn’t ever reboot because of that. You’ll need to check the reboot guide for a fix. Some apps from the big players are known to cause reboots, Facebook and Netflix for example, because they don’t play nice by the Android book. I’d not be surprised if Waze is in the same category.


Hi, no need to apologize, neither this forum nor the topic are exclusive. Anyone’s welcome to contribute.

Well yes, this is almost all you can get out of tha thing at once.
Anyway, it should just as any other device cope with it without rebooting due to overheating.
I think there is only limited gentle tweaking left for you. On some things I am not fully sure but could read in this forum in the past about others what actions they have done to get things better.

  • GPS has three different modes depending on accuracy. High accuracy (seems to be default) needs the most energy. Try out if the two other modes (one is “battery saving”) work for your needs. This was often suggested in this forum and helped other users here. (settings->location->mode)

  • Two sim cards, just as me. If coverage e.g 4G is not reliably given at any time
    (as you are moving in your car) and you don´t need the fastest net actually, you could set it to 3G only as long as your trip goes. This way it is maybe not necessary for the phone to regularly try to reconnect.

  • Waze - I think this would not make any sense being used offline :smiley:. Some other conventional navigation apps can do offline. If just being on a hike or so.
    There is not much difference between navigation apps if it comes to their demands. It´s rather their heavy (real-time) calculations running in the background keeping the phone sweating.

  • USB charing, I don´t know what this is. But I can tell you something about USB charging…:wink:
    Of course this heavy stress needs to be powered and will cause quite some heat. I would recommend to start-off with a full battery and immediately charging (plug-in) in the car - why? If the battery is fully charged already, the charging is only keeping the level up to it´s max. So the current flow is mainly supporting the phone while the battery is hardly charged. This way it´s the only current which causes heat. If your battery would be lets say half way discharged while having all this stuff going on, the charging current of the battery (and more heat development) would come on top.
    Yes - there are specialists rising their fingers to remember the 20%-80% charge rule. But this is no permanent state and a better way as frying the phone.

Also the environmental temperature has influence too and direct exposure to sun light.
I hope my suggestions also can support you to have a more reliable phone operation.


Yes, seems so.
I think GAFA are too large meanwhile and have too much power and influence.

Probably not before their “convenience” factor or personal benefit drops. But for those the next trick waits around the corner already.

Some of the GAFA only disturb me very little. I can easily go without Apple and Facebook. There are still some ways around Google. But most horrible to me seems Amazon. Avoiding purchases from them to find an item somewhere else increasingly becomes a pain in the …
To me it looks as if the founder does not even know what social values are. Having a lot of money is one thing. But not knowing how to use it in a social way another, at least partially. He seems to think if he offers even more home entertainment to the society that´s all to keep them glad. But it´s all only to get them addicted and even more spied out. No social/moral values at all. Let alone having no idea who actually got him that rich.

That´s also interesting for me. Usually task scheduling is all about priorities. Is there any chance to take influence in this? (as root??)
Your issue about updating the CPU state looks like being a priority issue.

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After much testing, I’m making version 1.0 of the Battery heat control flow available in the Developing area. It has been extensively tested and I’m quite happy with this version, it really helps to reduce battery heat, but keep in mind that you use it at your own risk, no guarantees are offered.

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Hi Patrick,

in past month I´ve tried different settings (different app, offline maps, etc). I think the overheating in CPU area is caused especially by the data on when the phone is moving.

When I used offline maps, having only GPS on was ok.
When I am using maps or any web browser and have data on and I am at the same place, it´s still ok.
But when I have data on and I am moving in any way (with car, train), it´s overheating quite a lot. In train with data on and just using web browser it can go to 70-80 Celsium degrees.
In car with the previously described settings it can go even over 80 Celsium degrees.
Setting data to 3G didn´t help (in terms of decreasing temperature). Having the battery fully charged before I start using navigation helps a little. Or at least prolong the time untill the auto restart of the phone…
Now is the question what will help…? New update od Android OS? Or should I try FP Open OS or any other?


That sounds worrying.
After having tried all this you could go for FPOOS or LineageOS. But this change may turn out being time consuming until you have everything back in place to your needs. Android 7 will need some more weeks of development.
With help of this forum you will surely succeed though, not having to stumble over every obstacle.
Better performance and stability can only be checked after finishing the task.

Before you take on this approach the last step could be a “factory-{data}-reset” or try the safe-mode prior to this as there isn´t much more to loose. Of course backup all of your personal data such as pictures, music etc.
Also you could in advance strictly go through your (all)apps list in settings
and “force stop” apps you have individually installed which you are not using permanently.
This could take some load of the cpu and reduce data usage as closed apps does not automatically mean being inactive and not using your data contingent.

This is my usual system state:

Since a few recent Google updates it turned out to be more active as before being permanently listed here too.

I believe the list of many other users here is noticeable longer which means more stress on the cpu, ram and battery.
Atm I don´t have anymore ideas what else could help in your situation.

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Hello there!

Related to overheating due to GPS activity: using OSM And (Open Street Maps’ app) + GPS signal in FPOOS was draining the battery really fast and it would keep draining even if I closed the app and I shut down the device. Really, with FP2 shut down, the battery would keep going down and when I restarted again, it was still draining.
What could I do in such situation to really stop the processes that were draining the battery? And is there a way of using OSM without having such a huge drainage?

Regarding this:

If I force stop any app will it prevent from being active at start next time I boot my FP2?

I´m on FPOS btw. I believe users here also running FPOOS can be of better help.

This depends on each single app. Some apps (e.g. Osmand) are installed as “device administrators” by default which cannot be forced to stop unless this permission is being taken away again (on Lollipop ->settings->security->device administrators).
But most third party apps should keep silent after being forced to stop until next use. For my experience even surviving reboots and only wake up when actually launched again.
This mostly excludes Google apps/processes though which may start immediately shortly after being forced to stop.
Some apps like firewalls may have the specific permission to automatically start on reboot which is meaningful to be set.

“Closing” an app does not necessarily mean to finally stop any of its actions continuing in the background. Often only the GUI is killed. Some apps offer a “quit” or “exit” button in the menu. These then usually do fully quit.

OSM counts as a battery killer. Not as much as PokemonGo, but it needs some careful tweaking to get it working without running low on power even while charging the device. Better start up with an almost full battery to have a longer backup. Reducing the GPS precision mode to battery saving or device only can help a bit but has drawbacks. Having only the minimum radio options enabled also helps to save some power.
You could try out system monitor (lite) to see which apps are using a noticeable amount of cpu time. This could help to sort out third party apps which you may want to force stop as you don´t regularly use them.

There should not be anything going on in the background when the phone is completely powered-down. The battery drain should be at a minimum (if nothing is connected to the phone). Otherwise this could show a defect of the bottom module.

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I’ve suffered with a hot FP2 for months. I note the heat comes from the CPU, not the battery. I’ve previously looked at battery usage and this suggested wifi and screen were the main drains - not very helpful!

I recently checked data usage and to my surprise found that Google Chrome was the main drain, using much more data than my most-used apps. I rarely use Google Chrome browser, so it should be near the bottom of the list. I use Lightning browser and a few others. I can only assume Google Chrome is active in the background.

Android would not allow me to uninstall Google Chrome, so I disabled it and uninstalled the updates. Amazingly, the very next day, I got to lunchtime with 91% left on the battery - a new record!

I have since noticed less heat from the FP2. As I type now it is Sunday evening and I still have a 55% charge. I hope my experience helps other users.


There were several complaints here about the CPU/GPU being too hot.
Often it was stated that a program was draining the battery for being permanently active in the background (GUI closed but background services still active).
Good for you that you could so quickly find the cause and solve it. You could even save a bit more energy by disabling and/or “force stop” other never used apps or apps which you only use once in a while (only by occasion or per week/month).

So I assume now with this experience you wouldn’t necessarily state that FP2 in general has a poor battery uptime.
As this highly depends on the individual use and therefore imho cannot be generally argued let alone compared with other handsets with similar hardware as often done.