hi guy's been a while since i last needed your help.anyway the old faithfull has given up the ghost.i was on it the other night when all of a sudden the computer shut down as if the plug had been pulled ( no warning,no beeps or blue screen).i have had it happen a couple of times in the past, but on reseting the switch on the power supply it fired up,but this time nothing.i took the side panel off and gave it a good clean (lots of dust),and reset the switch, turned the computer on and the cpu fan spun for about a second, as if it had received a minute residual current,also the green "on" light gave a dull blink that lasted less than a second.my thoughts are change the power supply unit,do you think this could be the right path to take?

Sounds like a good first step.

just a quick update for anyone with a similar problem.connected up new power supply and the computer fired up,everything now o/k

Thanks for the update.

Let us know if we can help further in the future.