Dead pc, green LED on motherboard flashes

Power the machine off at the wall socket leaving the cable connected. Hold the power button on the machine in for 20 seconds or so. Release the power button, switch the mains power back on and try it again.

Sometimes power supply units get into an odd state, that may clear it.

Alas, no. Motherboard LED still blinking and no life.

Do you have another PSU that you can try? If not you could try removing power from all components in the machine apart from the mainboard to see if its one of them causing the problem.

I'll try that. What does the flashing green LED mean?

Depends on the motherboard. The manual might tell you more, check the manufacturers website for it.

Did you unplug any network/telephone cable you may have had plugged in to it?

It is sounding like the power circuit on your MOBO has given up. It isn't supplying any/enough power to components to start-up.

A spike in the telephone line/network cable may have affected it. If not, it could equally be a coincidence that your motherboard has decided to give up, just as a storm hits.

Er, no. :(

I don't have a spare power supply. Should I go out and buy a replacement and see if that fixes it?

Thanks - I'll go try those things and get back to you.

Thanks - it was the PSu. But in removing, I had remove the CPU heat sink, and in the process detached the CPU by accident, and bent the pins trying to get it back in. I then had to by a new motherboard because an AM2 is really too old, which in turn required new memory...