I had a computer that was working fine for over a year, then suddenly it started to shut off, it got so bad that I press the power button and in around 30 seconds while booting Windows it would shut off, then 20 seconds, then 10, then it refused to start all together.
So I bought a new PSU (850 W Thermaltake, the old one was a 550 W Corsair) thinking that was the problem. I fitted the new PSU now and it's the same thing - I press the power button and my fans start for a split second (they have LED lights on them, so the lights come on) and then everything goes off again.
I thought maybe it was my power button that was loose on my computer. Luckily I had another chassis nearby so I disconnected the power switch from the old one and put in the switch from the new chassis. But when I pressed the power on the new chassis, it's same thing, it blinks for a split second and turns off again.
Double checked connections from the PSU to the CPU power as well as motherboard power, it's tight. It's pretty unlikely both the PSUs have the same exact problem so I am lost.