Is there a software for PC,for testing the Samsung Galaxy S5 Duo's CPU,which overheats?

[Maq Attaq]

Hi,
my Samsung Galaxy S5 Duos's CPU overheats,if I even only surf the web!
The app called CPU Temp,shows me CPU's temperatures up to 80 degrees Celsius,while I am searching the web or running any application, if I don't do anything with the phone the CPU's temperatures are between 38-45 degrees Celsius,if I start to do anything the CPU heats up to 55-63 degrees Celsius immediately!
So my question is:is there a PC software for hardware diagnostics for my phone?
And why does my CPU overheat?Could it be a hardware issue?
p.s I have flashed a few custom ROMs,thinking that the problem is in the software,but the problem is the same on all of the ROMs!
When I flash a new ROM,I always wipe all the data with TWRP and after the flashing I always install the same apps.Is there a possibility for some app to be the cause for the overheating and if there is how could I check that?
Please help me as soon as you can!
Thanks in advance!
Best regards!

 

[ironass]

I think that some or all of your problem could be that you are rooted and running the, "Nightly", or beta test ROMs of Mokee, which are similar to CyanogenMod ROMs. See your post, here.These are updated on almost a daily basis and are not always stable. The latest Mokee ROM for your model, G900FD, is MK60.1-klteduos-201606051442-NIGHTLY.zip. See, Mokee Open Source. You can either...

1. Download and install the latest version

or

2. Flash the stock Samsung firmware to your phone

Check if either of those solves your problem.

 

[Maq Attaq]

Dear ironass,thank you for replying to me!
I did everything you told me now and now the phone is running on the stock Samsung firmware( Android 6.0.1).
I realized that the phone heats up randomly,it doesn't heat up while watching videos on YouTube or playing music,but more when I am web surfing!
But now is more better than it was running on the Mokee ROM!
But why does the CPU overheat anyway?

 

[ironass]

Why do Android Devices Overheat? Here are Some Solutionshttp://www.droidviews.com/why-do-android-devices-overheat-here-are-some-solutions/