Pc freezing mid game

[ello.best11]

Okay so i have this problem where my computer completely freezes in the middle of my game(s)
and i hear a high pitch sound from my headphones.
Fist my specs
Windows 10 Home
Intel i5 2500k clocked at 3.3 GHz
Gigabyte GTX 960 4Gb running at 1266MHz
Gigabyte Z77M-D3H
16384 MBytes of ram (8Gb recently added) 1600MHz
550 watts
500Gb Toshiba Black drive
So i had this problem after i added 8Gb's of ram (exatly same) so now they are in 4 channels.
I have stressd my CPU but i didn't get the problem i have trtied to delite temporary files
Happy for answears

 

[ello.best11]

I have also tried stressing my GPU with Ungine Heaven And stresstesting my ram with memtest and using CPUZ to stress my CPU with no results i have the latest drivers for CPU and GPU, i do not know how to update RAM drivers i only get the problem when 1-2 hours in to the game and the PC crash

 

[ello.best11]

BTW my network card is a QUalcomm Atheros AR8151 PCI-E
I have run a HDD test from CMD too
When the Pc freezes i cant do anyting like ctrl+ alt +del and numlock dosen't work to turn on or of

I am having a hard time finding the problem