No Motherboard Light

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ellissitzky

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Sep 22, 2010
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The Problem

I transferred a working PSU to a machine with a dead one. I was all set, the motherboard light was lit up, I hit the power, and the light turned off, and now I can't get it to come back on.

What I Tried

I tried draining the PSU power, resetting the CMOS, reconnecting all the cables. No dice.

The Backstory

It all started when my band lost the power cable to an amp. I borrowed the one from my desktop to use for a rehearsal. About a week later I rehooked up the cable and my computer never turned back on. I transferred the aforementioned working PSU to the machine and voila, it worked. I transferred it back to it's original computer thinking I wouldn't need it but I'm in the process of RMAing the PSU so I decided to transfer it back to the down machine to use temporarily. That's when the current problem occured.

Previous Motherboard Issues

Perhaps some of these issues may be occurring because of the motherboard. In the past I've experienced issues such as hard freezing where no BSOD shows up, the ethernet port died a while ago, and sometimes the input devices hooked up via USB stop working and when that happens those USBs will be unusable until reboot.
 
Solution
InvalidError

Before you do, you might want to try the "paperclip test": short the PWR_ON# line on the ATX connector (green wire) to ground with a 12V fan attached to one of the mollex connectors. If the fan starts, you have at least some sort of +5VSB on there and output on 12V so you know the PSU is at least not completely dead. If nothing still happens, your PSU is likely busted.

A multimeter, even a cheap 3-digits ~$30 DMM, would still be better than guesses, light/no-light and fan turns/doesn't turn diagnostic: at least you get an actual number that is probably within 2-3% of the real value instead of very rough...
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StirB

StirB

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Jul 16, 2014
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So your saying both PSUs are dead now? Im not following your story all to well sorry, but a bad motherboard can cause the PSU to short out and not turn on so.....yeah :)
 
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InvalidError

InvalidError

Titan
Moderator
May 18, 2007
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It is only (sort-of-)common for PSUs with fake safety certifications and false claims of ATX-spec compliance. This is mostly the stuff of no-name/throw-away brands.

Almost anything with genuine claims of compliance and safety certifications will have protections good enough to prevent downstream damage most of the time since those are required by the ATX spec. Any credible vendor who values their reputation cannot afford to aim any lower than that.
 
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ellissitzky

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Sep 22, 2010
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That's good to hear. Both PSUs I used are Corsair.
 
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ellissitzky

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Sep 22, 2010
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I've completely disassembled the computer. I tried booting the motherboard with just the CPU outside the case and no light or boot at all. I double checked the working PSU with my other machine and it worked fine. Is it safe to say this mobo is dead?
 
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ellissitzky

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Sep 22, 2010
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Thank you, I looked over the breadboarding directions and made sure to do it exactly as mentioned. No sound, no fan, no light, no nothing.
 
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InvalidError

InvalidError

Titan
Moderator
May 18, 2007
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If you have a multimeter, check the voltage between ground and +5VSB (should be the purple wire) on the ATX power connector. If you have no +5VSB or if it is grossly out of spec, ACPI-on/off (the soft-power switch) won't work. The motherboard's +5VSB LED not lighting up indicates either that +5VSB is low/missing or the motherboard circuitry driving it is busted.
 
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E

ellissitzky

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Sep 22, 2010
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Unfortunately I don't. I should get one but at this point I'm going to send this sucker back to Gigabyte and cross my fingers.

 
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E

ellissitzky

Distinguished
Sep 22, 2010
14
0
18,510



 
Upvote 0 Downvote
InvalidError

InvalidError

Titan
Moderator
May 18, 2007
23,815
5,265
108,890

Before you do, you might want to try the "paperclip test": short the PWR_ON# line on the ATX connector (green wire) to ground with a 12V fan attached to one of the mollex connectors. If the fan starts, you have at least some sort of +5VSB on there and output on 12V so you know the PSU is at least not completely dead. If nothing still happens, your PSU is likely busted.

A multimeter, even a cheap 3-digits ~$30 DMM, would still be better than guesses, light/no-light and fan turns/doesn't turn diagnostic: at least you get an actual number that is probably within 2-3% of the real value instead of very rough guesses and probably (not) ok.
 
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