Computer randomly restarts mostly when I play games

[FrozenFruitTube]

For the last year or so my computer will randomly restart (mostly) when I am playing games, (eg, League of Legends, Overwatch, Starbound) but it has happened when I am just using Microsoft Word. I have replaced everything except my cpu and motherboard because I don't have the money to do so and wanted to explore every other option first.

When the restarts happen the screen will usually go black or some other dark colour and then for a few seconds I can still hear and talk in teamspeak then the audio will just loop and then it finally restarts after about 10 seconds.

I have replaced the PSU, RAM, GPU, added extra fans, formatted windows 7, since upgraded to windows 10, fully cleaned the computer out physically, checked the temperatures (its not an overheating problem), checked the logs (nothing unusual there), updated bios.
Theres nothing I can do to successfully force it to happen either, sometimes it happens after a few minutes of playing sometimes it will go a week with no crashes so its a very slow process testing if anything has fixed it. Ive tried running games on the highest quality and the lowest and it has no effect.

My Specs:
CPU: AMD Phenom II X4 955 3.2GHz
GPU: ASUS Radeon R9 270X
PSU: Antec 620W
RAM: 4x 2GB Kingston DDR3
MB: ASUS M4A88T-M
HDD: 500GB Hitachi

 

[NextGear]

FrozenFruitTube

Take apart your ASUS Radeo R9 270x and clean it and re-thermal paste.
If you computer continue to crash it's either video card or the PSU.

Last is change out the CMOS Battery.

You done everything I would have done.

 

[FrozenFruitTube]

FrozenFruitTube

Take apart your ASUS Radeo R9 270x and clean it and re-thermal paste.
If you computer continue to crash it's either video card or the PSU.

Last is change out the CMOS Battery.

You done everything I would have done.

I've re-pasted the R9, and the PSU has only recently been replaced, Ill try changing the CMOS battery when I get one.

 

[NextGear]

FrozenFruitTube,

Do you have a OEM fan or aftermarket fan on your processor?

 

[FrozenFruitTube]

FrozenFruitTube,

Do you have a OEM fan or aftermarket fan on your processor?

I have aftermarket fans and heatsink.
P.S I just replaced the CMOS battery, not very hopeful about that though.

 

[NextGear]

FrozenFruitTube,

Your CMOS will love for the new battery.

Drivers are up to date for all devices?
NO devices conflict?
What win 7 Service Pack are you on?

 

[FrozenFruitTube]

FrozenFruitTube,

Your CMOS will love for the new battery.

Drivers are up to date for all devices?
NO devices conflict?
What win 7 Service Pack are you on?

All drivers updated, rolled back, uninstalled completely, reinstalled tried all that.
No devices conflict its all compatible.
Im now on windows 10, I feel like the frequency has increased a bit since windows 10 aswell now that I think about it.

 

[FrozenFruitTube]

Bump

 

[NextGear]

FrozenFruitTube,

The last thing I would do...
Install a new video card and see what happens