Crashes when gaming & watching videos PLEASE HELP

[TheKurtzman]

The Build:

 

Proccesor :  Intel(R) Core(TM) i5-2320 CPU @ 3.00GHz

Motherboard : Asus P8H61-M LE/USB 3.0

Cooler : Cooler Master Hyper H411R

GPU : GTX 1050 TI

HDD : Seagate Barracuda 1TB

Case : Cooler Master Elite 311

Ram : 2x 4GB Kingston ( 1 of them is 1333mhz and the other is 1600mhz but i dont think it caused the crash as this ram has been a long time)

PSU : GX 550W Bronze

Case Fan: 1

 

Recently i been getting random crashes when I'm playing games and it would make buzzing sounds even when I'm browing the web or watching youtube it will still crash. So I thought it was the CPU getting hot and I change my new thermal paste which i bought but it still crashes. After that I decided to do a stress run on my CPU for 30 minutes and it did not crash and the temperature it went to the highest was 80 degree Celsius. I also did memtest86 for my ram to check if there's any error and there's no error with my ram so I was wondering what could cause it to crash. Is my RAM faulty because i use it for more than 6 years or is the power supply not enough which could cause random crashes? I did a clean install of windows and downloaded back all the newest driver but it still crash, I'm at lost here please lend a hand to me I don't know what can I do now.

[TheKurtzman]

Update: Just did a Windows Memory Diagnostic and it show up no error but still crashes when I'm playing game or even watching Youtube. Any help I can get over here?