Possible dying PSU ?

Hi guys, i'm having some problems with my system that i suspect might be the PSU giving up.

The problem goes like this : for the last 4 months or so, especially during gaming, my system freezes/locks down, it either shutsdown or it shows me the last frame of the game and there is no possible escape from this situation other than a hard reset ( the small reset button won't do the job, i must hold the main power button for 5 seconds in order for it to shutdown).

As an extra bit of info, i can't CTR-ALT-DEL or anything else.

I do have all of my GPU drivers and mobo ones up to date.

My system config is :

Windows 10 64 bit

Intel I5 760 2.8 GHZ

Ati Radeon 265x 2gb vram

1 TB harddrive

120 GB SSD Kingston SV300S37A

Gigabyte H55-UD3H motherboard

8 GB RAM

The PSU itself is MS-TECH 750W, MS-N750VAL

My SSD monitoring software shows it's in a healthy state, so i'm not suspecious of it. I know the system is quite old, but i'm in the process of replacing my rig with a new one, however, i need a few more months.

Thanks !