Please would you NOT listen to Shrikanth, I have had the same issue too, and I can, to this date, replicate the fault, it's the power supply main unit, all you do is replace it with a third party or an original one and you're good to go. I have posted this answer on another thread too, but I thought I'd share it too on here as the answer from the 'tech' is wrong! It has nothing to do with the motherboard.