Weird Problemm, Please help.

i have the identical situation, i cant talk for the original poster but i have a D14 light on when the PSU is in. does that still mean my mobo is fried?

more likely there is a problem with your motherboard. if you have he knowlege, go in and check the PWR_ON cables attaching to your motherboard from your case.. you might of accidentally pulled one during the PSU swapping routine. If everythings connected, your motherboard has met its maker

I have a PhD in Electronic Engineering and am a 5 year indentured Apprenticeship-served qualified Engineer in the UK.

I have come across this problem several times with certain motherboards. Ever since the ATX spec emerged motherboards have included an electronic latching switch arrangement which is triggered to latch by the front panel push button, and can be controlled by other circuits on the motherboard from SW and for functions like hibernation. This switching configuration has a final electronic switching element (power transistor) which is what controls Pin 14 of the ATX power supply.

On some motherboards this power transistor is not really adequate for the job under all conditions (of back emf which may be generated) and under certain circumstances of cataclysmic failure of the ATX power supply it (and occasionally other parts of the switching circuit) on the motherboard can blow out and become o/c. The power supply will not then switch on and at the most when you press the power button the only thing which may happen is that the power-on LED may light and stay lit if the latching circuit still functions. This is because the control circuit has latched but it will not switch the power supply on since the resistance offered by the power transistor is now too high.

The Asrock motherboards are amongst those which have inadequate power switching transistors. They are very good value for money and therefore economies are made in their design. If there is a cataclysmic failure of the power supply this transistor can therefore fail. Asrock are very bad in releasing any support information. This transistor can be replaced but you have to know what you are doing. If so you can substitute another more adequate power transistor, although you may have to also add components to adjust the bias position for the switch-on threshold.

In the case reported here it seems that this probably is the problem. A simple way to solve this problem and continue to use what is still in reality a serviceable motherboard is to either short-circuit Pin 14 of the power supply socket to ground, or to fit a switch to connect Pin 14 of the power supply to ground as an on/off switch. If you do this you will loose the ATX functionality for SW control of power switching and other functions like hibernation etc. You can alternatively get someone who knows what they are doing to repair the motherboard and the power switching circuit.

Make sure your power plugs are plugged on your hard drive and cd rom. Make sure you plugged your board back up snug, and try a different surge protector too. maybe switch the outlet plug to a different one. Make sure the switch on the power supply is on as it may of been turned off accidentally in the switch.

Could be as simple as the fuse blowing in the cable your using, have you tried another cable?

Do One thing in this case check if any led is glowing in the motherboard if yes the pull out the power switch connecter from motherboard , shorten the power connector on motherboard by any screw driver, if still it is not powering on, then the motherboard must have been corrupted. Abhi