Motherboard won't take power. Power supply wont turn on when plugged into motherboard but will with another motherboad.

recon5382

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Sep 17, 2017
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i have an asus P7H55-M PRO motherboard and a ocz modxstream-pro 700w psu. i had bought 2 molex fans and used an adapter on the psu, after that i tryed turning on the computer and nothing would start. no green light on the mobo, no fans spinning, and the psu wouldn't even start the fan. i have tested the psu and ruled out the problem to the motherboard. pleas help ive tried everything i can think of.
 

Sedivy

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Dec 17, 2016
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You can't really fix the motherboard when it's totally dead. It's rma or replace.
That being said, simply plugging in two fans into the psu shouldn't have by itself fried the mobo as it's not directly connected to the mobo at all. What might have happened is that your psu is going. Maybe voltages are unstable, outside the acceptable tolerances and mobo may have been struggling already.
http://www.wikihow.com/Check-a-Power-Supply (on how to check voltages on psu)
After adding additional load (though 2 fans is really minimal load wise), it stressed the psu so that mobo ended up dying? That's the only way I can see fans plugged directly into the psu affecting the mobo in such a way. Ideally, it should actually lead to psu dying, and saving the mobo but I've seen it go the other way so it's not unheard of.
You didn't connect the fans simultaneously to the motherboard and to the psu, did you?
 

Sedivy

Estimable
Dec 17, 2016
2,315
0
3,960
497
You can't really fix the motherboard when it's totally dead. It's rma or replace.
That being said, simply plugging in two fans into the psu shouldn't have by itself fried the mobo as it's not directly connected to the mobo at all. What might have happened is that your psu is going. Maybe voltages are unstable, outside the acceptable tolerances and mobo may have been struggling already.
http://www.wikihow.com/Check-a-Power-Supply (on how to check voltages on psu)
After adding additional load (though 2 fans is really minimal load wise), it stressed the psu so that mobo ended up dying? That's the only way I can see fans plugged directly into the psu affecting the mobo in such a way. Ideally, it should actually lead to psu dying, and saving the mobo but I've seen it go the other way so it's not unheard of.
You didn't connect the fans simultaneously to the motherboard and to the psu, did you?
 

recon5382

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Sep 17, 2017
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I connected one fan and it worked then I shut down and tries the next. I believe that's when my something failed. I then tried the other fan and It worked. After that I put both fans in series and that's when I couldn't get my mobo to come back on.
 

Sedivy

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Dec 17, 2016
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3,960
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The fan wire coming out of the fan directly is usually never molex. It's a very thin wire ending in a small square plastic adapter called 3 or 4 pin (depending on how many pins it has). Some cases will include automatic molex adapters, ie. they'll pre-plug your fan early on into a molex so you can connect to the psu. Sometimes these adapters split giving you the option to connect either to the mobo or via molex to the mobo. If you connected both at the same time ....that's bad. Usually it'll fry just the fan header on the mobo, but it can fry the whole mobo too if it has no protections on the fan headers. Can you take a pic of the wire, showing how you wired it?
Lemme see if I can find some pics so you see what I'm talking about.
 

Sedivy

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Dec 17, 2016
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recon5382

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Sep 17, 2017
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the fan is a molex connector. it doesnt connect to the motherboard, only the psu. this is what i boughthttps://www.amazon.ca/gp/product/B00JFLGD7O/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1
 

Sedivy

Estimable
Dec 17, 2016
2,315
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3,960
497
Huh you were right. I don't ever see those, but yeah that's going straight to molex, meaning you couldn't connect to the mobo.
You could try taking out the cmos battery on the mobo and replacing it after 10-15 sec, to see if that maybe resuscitates it. I'd tell you to try flashing bios, but if no lights flash on the mobo at all on startup, that's likely a bust as well.
There's only rma/replace then.
 

recon5382

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Sep 17, 2017
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ill try taking out the cmos battery and plugging it back in.
 

recon5382

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Sep 17, 2017
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popping out and plugging the cmos battery didnt work.
 

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