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Weird power supply issue

Last response: in Systems
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February 8, 2010 4:38:39 PM

Hello. I bought a new case for my home pc and put it together yesterday. in the previous case everything worked fine but it was a little cramped so i bought a bigger one. i put it all together yesterday and i couldn't get the motherboard to power on. i thought maybe it was the power switch connection, but my motherboard has a power button built on to the chasis and even that didn't work. Also the LED light on the motherboard was not illuminated. I checked my connections, the voltage on the psu, everything. I unplugged everything but the motherboard and it fired right up. after plugging back my connections one at a time i found the culprit. i have a ultra md2 media card reader that takes a power source. i was running this with the exact same power supply in my last case. With everything but the motherboard plugged in and this it still doesn't run so i know its not a wattage issue. If i have the LED lights illuminating but the pc is off and i plug this in, the LED shuts off and the PC wont power on. The only thing that has changed is the case. Also my psu is making a grinding noise but i believe that is just the fan and possibly unrelated. Any ideas??
February 8, 2010 6:31:05 PM

Did you ensure that the motherboard is properly grounded to the case with the little elevators?
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February 8, 2010 6:36:53 PM

Yes I did. It is. It will power up just fine without the memory card reader plugged in. when i plug that in, its completely dead. no power.
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February 8, 2010 6:46:21 PM

The patient says, "Doctor, it hurts when I do this." "Then don't do that!"

Some PSUs will shut down if they detect a short.
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February 8, 2010 6:47:23 PM

Lol. yeah well i need to use that leg!!!
Yeah i'll see if i can rma it. could be a short. thanks
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a b B Homebuilt system
a c 77 V Motherboard
February 8, 2010 6:52:00 PM

Are you sure you're not plugging in the card reader to the wrong header on the motherboard? That would cause a short. I've seen people plug USB devices into the HD audio pins.
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February 8, 2010 6:52:26 PM

Keep in mind that the PSU may be incorrectly detecting the short. It's not automatically the card reader's fault. I'm not an EE so I don't know how to test this without switching components.
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February 8, 2010 6:57:03 PM

Well actually the memory card reader isn't plugged into any usb ports at the moment. i disconnected everything to test. There is a seperate power (standard like a cd rom power) connection on the memory card reader. that was what i was referring to when i said plugging it in killed power to everything.
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