You can reset the Windows if it isn't to much trouble for you to install again all the software back together. Resetting reinstalls Windows 10, but lets you choose whether to keep or not your files.
This might solve the problem caused by software and it will save you more time than to try to troubleshoot by your own. The disadvantage with this method is that if it doesn't solve the problem then you have to troubleshoot anyways.
If you don't choose the windows reset step then following the method below might also help you fix your PC.
70 C temp CPU while you gaming it's a bit high depending your cooling system.
70 C idle CPU temp. it indicates that there is a hardware problem f.ex. with your cooling system or you might have a software problem (a malware runs at the background and eat CPU resourses).
To eliminate the latter boot your PC and open your Windows task manager then check if there is high usage of your CPU by any kind of suspicious program or service. Use your Antivirus/antispyware program and scan the O/S.
To check out the hardware part.
Take a look at the CPU fan speed while you gaming. Download a software that reports the RPM of CPU fan like speedfan
http://www.almico.com/sfdownload.php
Check also the temperature and fan speeds of your GFX card through Nvidias Geforce exp. software or the MSI afterburner.
http://download.msi.com/uti_exe/vga/MSIAfterburnerSetup.zip
You can also stress test individually the PC parts until you find the one that causes the problem.
Do a RAM test. Use the
Windows key + R keyboard shortcut, type
mdsched.exe, and click
OK to launch the tool.
Download the Prime95 for the CPU.
https://www.mersenne.org/download/#download
and the FurMArk for the GPU.
https://geeks3d.com/furmark/downloads/
Good luck and I hope the above help you to find a solution.