CPU Overheating Problem on Galaxy Note 8

Key Lime 314

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Following up on this thread, I've long since determined that I have a serious CPU overheating problem that is badly compromising the usability of my phone, and I expect is leading up to its eventual demise.

The phone reboots whenever the CPU temperature gets up to around 160 degrees F. If mess up and let that happen, it tends to reboot repeatedly if I don't have my ice pack to lay the phone on within arm's reach (and that has happened even with an ice pack) because the CPU temperature spikes late in the reboot process and keeps triggering more reboots.

I looked up how to measure the CPU temperature and wrote an Automagic script to monitor and log the temperature, and to sound an alarm if it reaches 150 degrees F, so I can immediately stop charging it, stop using it, and grab an ice pack before it reboots. I frequently cannot get away with using and charging it at the same time, and sometimes it will overheat just charging it and not using it, or just using the phone while not charging. If I go for a walk outside during the day, I have to keep it in my pocket with an ice pack, and if I ever wanted to use it for something like Pokemon Go, it would be out of the question. I never reboot deliberately without first resting the phone on an ice pack, and even then the CPU temperature will spike at over 130. When the CPU gets hot, I can feel a warm spot in the area of the display and back of the phone where the CPU is located with my finger.

This is NOT a battery temperature problem. I monitored and logged battery temperature while I was at it, and at no point over the past couple of months has the battery ever exceeded 103 degrees F. (and it's almost always much cooler than that). Also, I don't have any other problems I have seen with failing batteries, and AccuBattery agrees that the battery is in good condition, for what it's worth. (Besides, it would have rebooted from an overheated CPU long before the battery would have a chance to get crazy hot.)

I did most of the usual stuff you are supposed to do to troubleshoot this sort of issue. The updates are current, and nothing changed when Pie rolled out for me shortly after this ordeal was already going on. Uninstalling (most) apps resulted in no change. Booting into Safe Mode, I could no longer monitor the CPU temperature, but I could feel the telltale warm spot on boot up, and I used the web browser while charging the phone in Safe Mode, and sure enough, the area of the display and back of the phone near the CPU became noticeably warm, just like it normally does when I run into CPU temperature troubles.

Short of trying a factory reset, I think I've ruled out a rogue app about as well as possible. I also calculated the average daily CPU temperature over time from the logs. I only included days that I work, where I both use the phone less, and the patterns of how I use it are more consistent. Over the past six weeks, the average 24 hour CPU temperature on workdays has increased from about 99.5 degrees F to about 102 degrees F. This leads me to infer that there probably is a hardware issue that may be getting a little worse over time. I was hoping it could be helped with thermal grease, but a quick search didn't convince me that thermal grease is factor in keeping phone CPUs cool (not that I've ever learned much about the hardware, so maybe it is for all I know).

The obvious next step according to the conventional advice out there is to do a factory reset on the phone, but 1) I really don't want to because it is a hassle (ironic I know after the troubleshooting, and the temperature logging and the ice packs). More importantly 2) granted, I don't really know what happens when you do a factory reset, but I can only imagine that it would hit the CPU a lot harder, and for a longer period of time than a simple reboot, which already gets the CPU pretty hot even with an ice pack. Frankly, I am afraid that attempting a factory reset might brick my phone, not to mention that I am skeptical as to whether it would fix anything.

Of course, the phone is out of warranty now. I will probably eventually end up calling Samsung, but I fear it might be unsatisfying and probably quite expensive if I were to send in the phone. (The upcoming Galaxy Note 10 is looking mighty enticing!)

I am hoping for a response or responses that would provide a good sanity check for my assumptions and conclusions. Do you agree with them? If you are knowledgeable about this kind of thing and see that any of my conclusions seem wrong, please shoot them down and explain why. Did I overlook anything? Could it be as simple as bringing it in to a local phone repair shop for thermal grease? (I'm not an open-case kind of guy, myself.) Do you think it really is safe to attempt a factory reset, and have a compelling argument that will convince me to lay aside my misgivings? If so, I could possibly reconsider it. Did I overlook any other options? By the way, this all started suddenly three months ago with no previous problems.

Thanks,

KL 314
 

Golfdriver97

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I am hoping for a response or responses that would provide a good sanity check for my assumptions and conclusions.
Hi. I'll take a stab at this.

Did I overlook anything?
I don't think so. I think you have covered all possible solutions short of a reset.

Could it be as simple as bringing it in to a local phone repair shop for thermal grease?
Had to consult iFixit to see a teardown. I was expecting thermal pads, not paste. From what I saw, there is neither in the phone, so adding that won't do much good. A pad would be a better way to go, as some thermal compounds are electrically conductive. But, since there is nothing there like a pad or compound to help with cooling, I highly doubt adding something will be easy. A pad would also add thickness that the phone was designed without. Getting the phone to close again would be a pain.

I am hoping for a response or responses that would provide a good sanity check for my assumptions and conclusions. Do you agree with them?
I can see the point of setting up a phone post a reset will overwork the CPU to a reboot. However, if this thermal issue is stopping you from using your phone as you normally would, I don't think you have much choice.

I do want to counter this:
I really don't want to because it is a hassle

It's really not that much of a hassle anymore, unless you have a lot set up on your homescreen. Even then, if you have a third party launcher like Nova, you can back it up and restore it when the phone is done updating.

Overall, I think if you have a solid backup device, try resetting the phone. Even if you contact Samsung, they will probably have you do this as a troubleshooting step anyway.
 

Key Lime 314

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Thanks for the good sanity check. It's a shame. I've decided if it doesn't get significantly worse, I'll maintain the status quo and use this as my excuse to donate an arm and a leg for the Note 10 in a couple of months that I've been drooling over anyway. I'll do the factory reset if it does get a lot worse or once I have the Note 10. If it outright dies, there's always my underwhelming spare backup phone until the Note 10 comes out.
 

mustang7757

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Thanks for the good sanity check. It's a shame. I've decided if it doesn't get significantly worse, I'll maintain the status quo and use this as my excuse to donate an arm and a leg for the Note 10 in a couple of months that I've been drooling over anyway. I'll do the factory reset if it does get a lot worse or once I have the Note 10. If it outright dies, there's always my underwhelming spare backup phone until the Note 10 comes out.
Playing intensive games will shorten your battery life and could make it run warmer or overheat playing extended periods of time