Question PC turning off and refusing to turn on again

[Flying Pegasus]

I have 2year old PC which was running fine until late. It's no high end pc in any way. It's gotta G4560 and R7 360. Lately, my PC started malfunctioning. The HDD light in the front, which never before has showed it's existence, started blinking red Everytime I run my PC. And my PC would turn itself off after 20-30 minute usage(sometimes even less) and then won't turn on. All the fan will start to spin and the leds will light up for a second, then the computer will turn off. This will happen everytime. After a day or two if I try to turn it on then it will work for sometime and then shut down itself and same thing happens.
I am almost sure it's my PSU doing this but can't be too sure. If someone could help me it would be really appreciated. I did the paperclip test on my PSU and it worked fine. When the problem starts, if I remove the power to Cpu(processor) then the computer won't turn itself off(ie. Fans will continue to spin). And when I plug my CPU power back in it will immediately stop. HELP!!

 

[Flying Pegasus]

I tried unplugging my Gpu and running on the Intel hd. And removing the connection to my HDD. Made no difference. So I am not at all sure if it's my PSU or my mobo or my CPU failing.


P.S there is no dust build up cause I clean it regularly.