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PSU problem

Last response: in Components
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July 27, 2012 11:38:17 PM

Hello,

I just tried to boot up my first build, and didn't get any video or POST sounds--I tried the troubleshooting steps that are posted on this forum, and right now have the motherboard out of the case, with only the CPU and heatsink installed. When I plug in the PSU (I definitely have both connectors plugged in) I get a green LED on the motherboard, but the CPU fan doesn't spin up and the fan on the PSU itself doesn't either. Oddly, earlier when I was troubleshooting, still inside the case, the CPU fan did work, and so did 3 out of the 4 chassis fans, even though all 4 were securely connected. This feels to me like a bad PSU, but before I send it back, just wanted to ask if that sounds right to anyone else.

More about : psu problem

July 28, 2012 12:45:22 AM

It sounds like you are correct. If the fan built into the PSU isn't working then something is defiantly wrong with it. You should go ahead and send it back and get a new one. I hope you get your new PC up and running without any problems past this one.
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a c 80 ) Power supply
a c 218 à CPUs
July 28, 2012 1:27:08 AM

Before sending it back you should do the paper clip test to make sure that there is a serious enough problem and it only takes a minute to do.

http://dodji.seketeli.com/downloads/shuttle-psu-paper-c...

Also while you have the MB out of the case and the psu connected are you useing a screw driver to short the two pins on the MB to attempt a start up?
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a b ) Power supply
July 28, 2012 2:27:47 AM

Some modern PSUs the fans don't spin until they need to. I'm not yet convinced the psu is the problem since you're getting LED on the motherboard. What model motherboard? Does it have other debug LEDs?
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July 28, 2012 2:51:42 AM

The motherboard is an ASUS P8Z77-Pro, and the LED I'm getting now is green, mounted next to the 24-pin connector to the PSU. I'm not sure whether there are other debug LED's on it.
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a b ) Power supply
July 28, 2012 3:21:14 AM

Hmmm...look at page 2-15 of your manual. I think that is the DIMM LED, which is telling you your RAM is not completely seated. I wish ASUS put the 2-digit debug LEDs on all their motherboards...that would tell us for sure.
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July 28, 2012 3:41:26 AM

Ah, didn't see that page of the manual--it's not the DIMM LED, it's the standby power LED that's on (incidentally, I don't have any RAM on the board right now--I took it out as per the troubleshooting instructions).
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a b ) Power supply
July 28, 2012 3:44:51 AM

Still no fans spinning. Given the light, smells more like motherboard or a loose connection than PSU.
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a c 80 ) Power supply
a c 218 à CPUs
July 28, 2012 4:19:31 AM

If you have the fans connected to the psu and you do the paper clip test you will get the fans to spin and that will at least tell you the psu is ok and you can move on to the motherboard.
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July 28, 2012 4:50:00 PM

Looks like it's not the PSU--I bridged the connections on the 24-pin connector with a paper clip, and also hooked up a heatsink fan to the PSU. When I turned it on, the PSU fan spun up for just a moment and then turned off, while the heat sink fan spun up and continued to spin. Motherboard the likely culprit? Any way to test?
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a c 80 ) Power supply
a c 218 à CPUs
July 28, 2012 7:11:33 PM

Once you have verified that he psu is working then you plug in the 24 pin main MB connector and the 4/8 pin atx cpu power connector. These are the two power connectors that will power the motherboard , so next you either connect the two pin power switch or take a screw driver and touch those two pins that are marked for the pwoer on switch. The power on is a momentary switch so all you have to do is touch the two pins for a moment and then back off the screw driver , you don't have to hold it there but at the same token don't toch the pins for a half second either. That should start the motherboards bios sequence and should not shut off untill you unplug the psu or turn the psu off.
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July 28, 2012 7:42:57 PM

Done--I have the same power LED, and now the red DIMM LED (which is expected, since I don't have any memory installed right now). The heatsink fan is spinning, and so is the case fan I have plugged straight into the PSU. It looks like the bios sequence is working, but shouldn't I be hearing some beeps from the motherboard speaker? Unless I have it plugged into the wrong place--it's on the bottom left of the motherboard right now
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a c 80 ) Power supply
a c 218 à CPUs
July 28, 2012 7:54:35 PM

You need to have the memory installed to hear the bios beep. You will only get the single bios beep when you have everything installed and they all pass the bios check. You should hear a series of beeps with the memory not connected but as you said you may not have the case speaker connected to the correct pins. The case speaker pins are located next to the power on switch and reset switch pins at the lower right of the MB.
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July 28, 2012 8:23:46 PM

Ah, you're right, it was plugged into the wrong spot. Plugged in correctly, I now get one long beep followed by two short ones, which according to the manual is the code for no memory installed. Putting in a stick of RAM and seeing what happens.
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July 28, 2012 9:00:00 PM

Okay, with RAM installed the red LED next to the PCIe slot comes on for a moment, then turns off with a high pitched beep. Then the red "boot device LED" comes on, and I hear one low pitched beep (the same pitch as the one for no RAM). I don't have a video card installed right now though--is it just recognizing the onboard one?
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a c 80 ) Power supply
a c 218 à CPUs
July 28, 2012 9:19:51 PM

If you have onboard video then yes it would recognize the onboard video. Does the red boot device led stay on? When all is ok with the bios boot sequence you should hear one beep and that's it , if you hear more then something is not right so when everything is connected including a hard drive then you want to heat one beep.
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July 28, 2012 9:55:03 PM

Plugged in the HDD and the external video card, hooked up to a monitor, and I get a BIOS boot screen--guess there was a bad connection somewhere the first time. Thanks!
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a c 80 ) Power supply
a c 218 à CPUs
July 28, 2012 10:03:33 PM

Godd to see your up and running , it doesn't take much to have the thing not work and that's why you have to check and recheck all connections and slots.
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