This is really strange.

I had a comp 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 secs while booting windows it would shut off, then 20 secs... then 10 secs, then it refused to start all together.

So I bought a new PSU (850w Thermaltake, the old one was 550w corsair) thinking that was the problem, I fitted the new PSU now and its 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 comp, luckily I had another chassis near by so I disconnected the powerSW from the old one and put ran the powerSW from the new chassis, press the power on the new chassis and same thing, it blinks for a split second and off again.

Double checked connections from the PSU to the cpu power as well as board mobo power, its tight. It's pretty unlikely both the PSUs have the same exact problem so am lost...

Suggestions?