PC keeps powering itself off

[Vanilla]

My PC has been fine for months. I just moved it from one room to another.

I turned it on and all was fine. Then - a fan started to make a racket so I thought i'd unplug it. I did so and tried to start again.

Now my PC gets a few pages into the boot (bios, mobo, etc) and turns off instantly.

* I have tried a different power outlet, makes no difference.
* I have tried unplugging a few things but no joy, the PSU is not overloaded.

Any ideas?

 

[Vanilla]

It was a case fan, I powered the PC off and unlugged it. It was powered from the PSU.

I've got it back online now, but I don't feel too cosy. Will report back it if does it again.

 

[Vanilla]

Yes, I got it out, I took the side of the case off. Swore at it, told it where it would end up, plugged everything back in the back and it turned on fine.....