When I push the power button on my PC case I am shorting two pins of a header on the Mobo. The result should be that pin 14 of the 20 pin ATX PSU should go active (low) and the PSU should power up. It isnt. The green LED shows that the standby 5V is present on the mobo. Does anybody know what is likely to be included in the mobo circuitry that will prevent the active signal being generated on the mobo? The mobo is an ASUS (model not known).

Welcome to PCHF

Does your motherboard have a 20pin or a 24pin connector for the ATX power supply?

The only way to work out a proper solution to your problem would be to get the exact model of your motherboard.

Does it not have a FCC-ID number on it, or at least a part number. Asus are normally quite good with putting the model number on the board.

See if these sites help

http://www.bluemax.net/techtips/ATXP...pplyWiring.htm
http://www.7volts.com/atxnotes.htm

Hi Zimbo, thankyou for the very useful URLs I've filed them for later use. The motherboard details I've just got off the board are:

ASUS A7V-E Rev 1.01

and it has a 20 pin ATX connector. Can you still help?
Regards John

Thanks for the motherboard model, I will start looking into that.

Lets just clarify something quickly.

What is the main problem with your system, I know you were talking about the whole pin14 thing, but to simplify it:

• Is it not powering up when you press the power button?

Also have you had this system working before or are you just trying to install it now.

Thanks Zinbo,
It's a second hand (Used) mobo that I would like to regenerate for my own use. When powered on the bench, the green LED illuminates, but shorting the two pins of the header (for case power switch) has no effect. No PSU fan, No CPU fan. The PSU is OK also the CPU fan.
Regards John

Which pins are you shorting?

Are you shorting the pins straight on the motherboard or are you using the power switch?

If you are using the power button make sure that the power switch is connected to the correct pins.
Check the attachment for the correct position of the power switch jumper.

Also make sure that the CMOS jumper is not set to on, otherwise the system will not boot.
The Clear Cmos switch on this motherboard is located on the left of the IDE slots and is labelled "CLRTC"
Make sure there isn't a jumper on those two pins.


You might already have a manual but if not then checkout this link:
http://www.motherboards.org/files/ma...1/a7ve-101.pdf

Attached Images

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