PC Freezes then restarts without warning

[Malifion]

Hello, I have been experiencing a very annoying issue with my computer since about late August of last year (2015) My computer will randomly restart while I am gaming, the computer freezes for a brief moment (1-5 seconds) during this period it is a frozen screen I can not move my mouse and all keyboard inputs are Useless
I started by reseating my RAM (did not work)
Opening side panel (did not work)
got a new video card (did not work)
installed a side panel fan (1 fan still not working)
I rearranged wires in my CPU to provide better airflow (did not work)
getting a new hard drive (did not work)
reapplied thermal compound to CPU and GPU (to new video card as well as old still not working)
replaced the CPU/Processor (still not working)
Cleaning out my computer (still not working)
switching to a new case (still not working)
I am beginning to think this is a motherboard issue or a PSU issue possibly heat sink as well
My GPU runs a steady 26 Celsius out of game and around 50-54 Celsius in game this does however happen in any game regardless of it being a very little graphic intense game like League of legends or CSGO or a more intense game such as fallout 4 this problem manages to persist I would deeply appreciate any help or suggestions anyone can provide I have also freshly installed Win 10 and completely wiped my hard drive to no fix
Here are my current Computer specs

Motherboard: Asus p5n32-e
Video card: Geforce GTX 960
RAM: 8g
PSU: Corsair TX 750 WATT
CPU: intel 2 quad core q6600 (2.40 ghz)
Hard drive: 2TB HDD (mechanical)

 

[basroil]

Try testing one RAM stick at a time.

If that doesn't help, reformat.

If it still doesn't work after that, replacement is the best option, your system is already >8 years old and should be left to die. You can carry over the GPU and HDD, but forget about the rest.

 

[Malifion]

Try testing one RAM stick at a time.

If that doesn't help, reformat.

If it still doesn't work after that, replacement is the best option, your system is already >8 years old and should be left to die. You can carry over the GPU and HDD, but forget about the rest.

 

[Malifion]

Ah yes thank you very much, that does make sense, given how old the system is thank you so much