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ASUS Motherboard P5e won't POST

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zillah

New Member
Joined
Apr 10, 2007
Hi

I have got ASUS Motherborad P5e,,,,yesterday it did POST today it did not work.

I can see SB LED lights up in green color

I removed all cards and RAMs and HD,,,,only CPU left, and shorted the pin for POWER SW,,,still noting worked, CPU fan wouldn't spin at all.

Unplugged the power supply cable that is hooked to motherboard and hooked it again

If the motherboard SB LED lights up, the power supply is almost certainly working.

Is there any other troubleshooting should I consider ?

Thanks
 

gottcha

Member
Joined
Feb 26, 2008
Location
wisconsin
Check all your connections on the mother board. Do you have the 8 pin power conector plugged in by the socket?
 

vgta88

Member
Joined
Nov 15, 2007
I have 2 boards that have the 5volt standby (i just looked it up it's 5vsb, might be separate from the normal rails so it could still be bad psu) light on but won't post. That doesn't mean anything. I have a feeling a bad power supply capacitor outputed bad voltage and destroyed a component on the boards or took out the voltage regulation circuit.

When my 2nd board(nf7-m) was working with the same faulty psu, the southbridge chip would not get too hot. When it made the board not post (after being unplugged overnight and then plugged back in, think the bad cap might have taken long or something to make the right power so blew something) the southbridge would feel somewhere over 40°C, well way over this to the point of being too hot to touch, i just didn't measure but i thought 40 was like hot water. (this is without post so the only voltage that should be doing this is the 5vsb.) 5vsb is also used so that your motherboard has the power to send the power on signal to psu, I believe) it has to be done by software because its a constant signal.

The thing is I don't know why 5vsb would make southbridge hot, maybe usb devices are powered through it via southbridge...and still powered when everything is off. this is to allow keyboards to wakeup the computer.

touch your southbridge if you don't have a heatsink on it. btw i'm talking about abit nf7-m and asus a7n8x vm 400 both are nforce2 chipset so it might be a similar thing only for these and maybe not yours.
i was paying attention to the power sw area on my motherboard when the psu messed my board up. I heard some really faint to kind of like static electricity poping. I don't see any venting, leaking, poped caps.

there are 8 small capacitors, 1 small mosfet and some really small mosfets that don't even look like mosfets in the area, I hope the motherboard power sw was not shorted and burn out somehow. and that the tiniest chips (smd) aren't dead.

The only other tests you can do is jumper your psu with the green wire to ground. and use a load tester to test that voltage rail's voltage and current draw to see if it is up to spec. if the psu is ruled out by that then it is either the cpu or motherboard. this can be done if you have a load (lightblub, harddrive, resistor) and a volt meter and an ammeter. if you are not technical don't try since you need to have a load similar to your psu rail's max wattage output. for example car lights run off 12v but there is no way it will draw 30 amps of current so you really need a more suitable load tester.

look, i'm having a similar issue as we speak so i'd appreciate updates. I'm gonna keep my power supplies and boards, i have spare cpu's. gonna see if I can revive the motherboards by learning some capacitor, mosfet replacement and maybe surface mount device(smd)soldering. (extreme) I need a multmeter and better iron. maybe ammeter. maybe even an oscilloscope.

I could have avoided this by re capping my powersupply unit if I knew about these types of failtures and had the tools available before hand. definitely gonna get my hands dirty so I can avoid this in a future build.
 
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