I just got my Galaxy S21 yesterday and it is amazing, fast, and looks beautiful but there is one major problem I've been having with it. If I try to do any sort of multitasking, the phone heats up to uncomfortable levels and displays a warning that it is too hot and for me to try split screen or pop up view when it cools down. For a phone that is supposed to be great at multitasking, this is a major flaw. I believe that this can be fixed through software optimization but as of right now this is very disappointing. I haven't even been using 5G yet. On my old Note 10±, I could run so many things at once without the phone even getting very hot but this one overheats easily. Even when charging, my note charges without getting so hot. This really needs to be fixed soon. I can't even run a youtube video in pip while browsing the web because it will overheat the phone. And it's strange because battery life so far has been phenomenal! I've gotten 2 days on one charge. Also, I saw that they recommended using the phone in environments between 50°-100° and my house is always at 70° or so which means that the phone should be running fine.
Update: I have since found out that one of the causes of the overheating is due to the 5G on this phone. When my phone is connected to my home wifi but I don't turn my mobile data off, it overheats and is very hot to the touch but after turning off my mobile data, the problem appears to be gone though not really since you should be able to keep your data on with wifi without overheating your phone. So just a heads-up until Samsung decides to fix this, make sure you keep your mobile data turned off when using a wifi network because the data syncing in the background is too much for the phone. So much for a "power efficient" processor I guess. This is really sad to see because now it seems that the Snapdragon variant is the one with the overheating as well as the Exynos so it's not necessarily a chip problem but more likely a problem with the 5G modem sapping too much power. SMH Samsung please fix this.😔
Update 2: After using my phone for a few hours, it seems that the problem has appeared again even with data off. I guess that using multi-window or picture in picture also causes the device to overheat. I had youtube in pip mode while staying g on the home screen and no other apps open yet, the phone still overheated. The image below is of me using pip on YouTube while browsing a website on Google.
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Same overheating issues as well. What's the solution? Replace the device? I already sent in my old galaxy phone for the trade im so it seems I'm doomed.
My phone charges kind of fast (around 3000 mA) when I first plug it in. Nowhere near the almost 5000 mA my S20 Ultra reaches in the beginning. BOTH of my phones throttle charging as they heat up, cause you know safety. However, the difference is the rate of overheating. My s20 ultra charges for way longer at higher speeds before slowing down due to heat. My s21 ultra takes maybe 5 minutes? before it starts to heat up and slow down charging to roughly 1500 mA.
I have mixed the wires and charging pad and same results both times. samsung brick and wire and anker brick and wire (even when mixed) don't make a difference. I tried taking off my case and still heated up pretty fast (i have the leather case from Samsung). I tried *not using the phone* and it still heated up relatively fast.
I have to decide to send back my old phone for trade in or send back my new phone + all the accessories and idk. Its kinda sad because the s21 has a lot of quality of life improvements that I prefer but the charging is a huge buzz kill
So if you haven't updated to the February update for the s21 ultra, don't. You'll want to skip this. When recording like 5 minutes of video the entire phone overheated and shut down. I was able to replicate this behavior over and over.
Update: clearing cache and factory reset did nothing to resolve the issue. Samsung needs to fix it with an update.
Update 2: rolling back to January rom using Odin fixes the issue. Do so at your own albeit minimal risk, but it does fix the issue.