ATX Power Supply Question

I'm trying to figure out if I have a power supply problem. Is one of the voltages still applied to the motherboard even when the unit is powered down but still plugged in? If so which voltage is it? I have noticed that some motherboards have a green LED on even when the unit is not powered up.

 

Yes, there is power when the computer is off and still plugged in.

Some clarification of what type of computer you are using would help. What problems are you having?

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Thanks for the quick reply. It's a home built computer with 350W Antec Supply. It's a 20 pin with the extra 4 pin plug. With the unit power up, all of the supply voltage measure good. This motherboard doesn't have an LED but I expected one of the power pins in the connector to be Hot even with the unit powered down.

The unit will not post, no beeps at all. The fans run, drive powers up. The CMOS battery is a little low 2.8V. Tried clearing the CMOS with the jumper and also removed the battery for awhile. Neither helped.

I also stripped the unit down to the bare motherboard and still no beeps.

 

if you have stripped it down to the mobo, and no beep, I would say try a new PSU, if that does not work, the motherboard is dead.:cry

If you are getting no beeps, double check the CMOS jumper. Make sure it is on pins 1 and 2.

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