Re: [Hampshire] PC powers itself off after grub.. any ideas?

Right...

Well it wasn't the power supply. Nice shiney new PSU with more power than
the old one, and it is still behaving the same.

Booting gets further depending on how many peripherals are connected,
without anything other than display and keyboard it will boot, but even
just connecting the ethernet cable means it won't get through the whole
boot.

It still feels like power, the more things connected the less far it gets
through the boot.

I've checked the temperatures and I'm 99% certain it isn't over heating.
CPU heatsink is still cool enough to touch when it powers off, and the
BIOS should warn with beeps at 65 degrees before power off at 75 so I
would expect it to be quite hot if that was the issue. Powering straight
back up and using the bios health check shows temp in the 35 degrees or
so, I wouldn't expect it to cool back to that from 75 that quickly.

Booting from a Linux live CD (well USB stick) doesn't work either so I
think it is unlikely to be kernel and software related.

Any other ideas? I guess next I look at replacing motherboard and
processor which is pretty much the whole machine replaced at that point.