So lately my computer has just been turning off suddenly without warning. To restart the computer you have to cycle the power switch on the power supply, if you don't, then the computer does not respond to the power button being pressed. Along with this, the air coming out of the Power Supply is very hot. Though what is confusing me is that the motherboard light stays on even when the computer suddenly shuts down. I recently replaced an old ATI 5750 with a new AMD 7950, which uses MUCH more power. I only have a 500w cheap psu. Does this sound like a PSU failure or something else? All help would be appreciated. Thanks.
Min Power Supply needed is 500W....but u have 500W PSU....i doesn't work at 100% efficiency .....just 80%...it means...u dont get 500W supply.....so u need 650 or 750W power supply
Sorry but that isn't what the efficiency number means. PSUs should always be speced bigger than the minimum however the efficiency number refers to how much power is lost in the conversion from AC to DC. In the case of an 80% efficient PSU approximately 20% is lost to heat. The higher the quality of the components and the better the architecture of the PSU circuit the less is lost to heat.