Question Computer randomly shutdown

[epicfails24]

My computer randomly shutdown. I was just at desktop with chrome open watching some YouTube then out of nowhere my PC shuts off instantly, it tried to restart once then turned off.

Oddly enough the front of the case still has the power led lit and the motherboard is still showing its getting standby power though now its just an rgb light.

Ive had the power supply for a while it is a corsair 750 watt which is only bronze rated though this happened right at midnight here in NZ so I can't even look at this till 2 moro.

I have completely unplugged the PC as i now dont trust the power supply to be on standby power overnight while i sleep. Dont want to burn to desth in a house fire.

I tried flicking the power supplies switch to off, unpluging the power cable,pressing power button on case to drain residule power, plugging it back in, flicking the power supply switch to on, this time the power led was off, i had hope, pressed the power switch and it instantly turns on and off, again the led light on the front of the case remains on until the power on the back of the power supply is switched off.

I welcome any theories and thank all replies.

 

[Lutfij]

When posting a thread of troubleshooting nature, it's customary to include your full system's specs. Please list them like so:
CPU:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS:
Monitor:

Corsair is the brand of the PSU while 750W is the advertised wattage. Bronze is the advertised 80+ efficiency rating. We will need to know the model(series) of the unit as well as it's age.

 

[epicfails24]

CPU: intel i7 11700KF
Motherboard: Asus Strix B560 gaming wifi
Ram: G Skill trident Z 2x16gb ddr4 3200
SSD/HDD: 500gb gigabyte nvme gen4, 500gb samsung 980, 500gb gigabyte ssd, 2tb wd hdd, 2xseagate barracuda compute 4tb hdds
GPU: gigabyte nvidia rtx2070 super
PSU: Coolermaster V750 750watt bronze rated
Case: Coolermaster hafx the old ancient one.
OS: Windows 10 pro 21H1 x64 bit
Monitors: Asus 1080p monitor, LG 1080p
144hz gsync compatible.
Cooling: ek rgb cpu block, 17,6 inch tube running to a XSPC 240mm thick rad, then to an ek bayres v4 pwm with a liang d5 pump.
Fans: 3 noctua nf12s, two at the top above the rad in pull. One rear of the case in pull. Coolermaster fan that came with the case at the front in pull. Its big though duno the size off by heart.

This is all off the top of my head and what info i can gleam looking through the cases side window.

The powersupply is a Coolermaster V750 its probably about 8 to 10 years old so im betting its that.