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Original topic:

S21 Ultra Exynos 2100 over heating even after update

(Topic created on: 06-09-2021 09:31 AM)
Laurian Stefan
Galaxy S21 Series

So I got the S21 ultra Exynos 2100 512GB a week ago and I noticed that the phone gets extremely hot even when doing frivolous tasks like notes, gallery, Instagram, even the screen turned on with 25% brightness  without actually doing something that requires a high processing power will make the cpu reach at least 40 degrees Celsius.

I'm using CPU Monitor to peek at my cpu performance and stats.

The Idle temp (first time turning on the screen after 10-15 minutes) is around 36 degrees.

It reaches 44 degrees while gaming and even playing music on YouTube with the screen off will get me to that temperature in just 10 minutes.

I started from scratch with the setup, I installed one app at a time, got no data from the old device.

I have the latest software version which was supposed to fix the overheating issue.

I use 120Hz and FHD but I noticed the overheating still happens with 60Hz as well.

My 5G is turned OFF, cpu limited at 70%, even with battery saver the phone still reaches the same temperature.

I still have the overheating issue even in Safe Mode.

Apps settings were remotely optimized by a Samsung technical support employee. He didn't know what to do and advised me to take it to a service.

This is my CPU status as I write this message.

Screenshot_20210727-200002_Cpu Monitor.jpg

 It seems like all the cores work at full speed but why does it have to be like this with only Google Chrome opened?

I'm wondering if this is a software or a hardware issue. If it's a software one I guess it can get fixed with a good update this time, one that will optimize the CPU usage in a smarter way, but I guess I'll find out in a few days since I'm planning on taking the phone to a Samsung Service for potential repairs.

Also, here s a screenshot of a benchmark I did a few days ago. The score is significantly lower than other S21 Ultra Exynos versions but the CPU stability seems to be 98% which is odd.




Galaxy S21 Series
Mine has been heating up again like mad. Charging up massively heat it up , I no it's supposed to do it, but this is well more than just being warm the back of the phone is scorching hot 🔥
Galaxy S21 Series
In my experience its been no different than any other high end smartphone of the last 5 years in terms of heat. There are inextricably weird scenarios where it does heat up, but it's rare and no different from any of my previous high end devices I've had before (S20 Ultra, Note 10+ 5G, P30 Pro, Mate 20 Pro, S8+ etc). What is noticeably better however is its battery life and performance consistency. No other phone I've had before can outlast it especially using the high end settings (WQHD+ 120Hz).
Galaxy S21 Series
Try using FHD+ and 60hz. The heat goes away it's 120hz and WQHD that's causing heat. I've tested it.
Laurian Stefan
Galaxy S21 Series

So I took the phone to a Samsung Service and they said the device has a manufacturing problem which can't get fixed and it should be returned right away.

Thanks for all your replies

View solution in context

Lord Hamad
First Poster
Galaxy S21 Series

Hi Guys

I tried everything mentioned in this article to solve my S21 ultra overheating Issue

No Use at all, my phone keeps heating upto 70c !!!! And that is insane

On idle, it would flactuate between 35c-40c !!!  Still insane !!

The final and effective solution I did was stepping down to the old firmware


I used Odin to format everyting and install fresh ROM because there was no option in samsung updates to roll back

Now my phone stays cool at 24c (normal room temerature) when idle and reaches about 30c on load work

At extreme cases when playing games it may reach 45c

But compared to the latest update this is very satisfying


I will never update my phone ever, not untill I see real action taken by samsung to fix thier software problem, Exynos is a poor execuse of a processor when compared to snapdragon, so I wish Samsung would optimise it to work without pushing it to compete with snapdragon performance because it will never compete unless they melt it down in your hands by overheating.

Good luck

Galaxy S21 Series

The SD 888 has more severe heating problems. I've seen a lot of phone models running this chipset, having serious problems with temperature: sony,xiaomi,oppo...Qualcomm really messed up this year with the 888 much like they did with the 810 if I remember well.