Question Motherboard not powering on

Feb 16, 2019
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I recently bought a cpu, 12gb of ram and a motherboard from a 2nd hand seller, when it arrived the motherboard was not turning on, the seller wont give me back the money so im trying to fix it, the motherboard is a msi H81M-P33, the cpu a i5-4590, one of the rams is a 4gb (samsung) one and the other a 8gb (crucial) ddr3, i've tested the psu and works fine, i've used it in other computer tests and it is working perfectly, the cpu is tested too and it works another motherboard of the same model (H81M-P33), the faulty motherboard wont power on, when i try to bridge the power on on jfp1 it doesnt do nothing, i've checked the voltages on those pins and it gives me 4,56v, i dont know if that's good because i read that it should give me around 3.3v, i also tried changing the cmos battery without any good results.

Sorry about my english im not very good at it haha.

I dont know what more it could be, would be nice to hear what u can tell me :)
 

Satan-IR

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Apr 18, 2014
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The fact that you have tested with a known working PSU and CPU and not working points to a dead board. Does the CPU fan work when you try to power the motherboard on? How about the PSU fan?

Mixing different RAM is not recommended, actually, it causes trouble and stability more often than it works fine. Try to boot with any of the two DIMMs the Samsung or the Crucial installed on the board. Although if the board is dead (likely) that wouldn't make any difference.
 
Feb 16, 2019
6
0
10
0
The fact that you have tested with a known working PSU and CPU and not working points to a dead board. Does the CPU fan work when you try to power the motherboard on? How about the PSU fan?

Mixing different RAM is not recommended, actually, it causes trouble and stability more often than it works fine. Try to boot with any of the two DIMMs the Samsung or the Crucial installed on the board. Although if the board is dead (likely) that wouldn't make any difference.
i've tried with just 1 module of ram, the vents are not spinning, the board is just not turning on, im looking for a way of fixing the board, some chip that may cause the problem or something to swap, i've got a theory that if the power on pins are giving me 4.5v instead of 3.3v there must be some resistor that is bad and actually i found that there was at least 1 resistor that didnt conduct anything, maybe because of a voltage surge. Im looking for some clue
 

Satan-IR

Reputable
Apr 18, 2014
622
5
5,365
133
i've tried with just 1 module of ram, the vents are not spinning, the board is just not turning on, im looking for a way of fixing the board, some chip that may cause the problem or something to swap, i've got a theory that if the power on pins are giving me 4.5v instead of 3.3v there must be some resistor that is bad and actually i found that there was at least 1 resistor that didnt conduct anything, maybe because of a voltage surge. Im looking for some clue
Just to make sure, by power on pins you mean the pins on the PSU 24-pin ATX12V connector? The green wire?

That (if possible) is the work of someone with hands-on experience with motherboard electronics and SMDs, nerves of steel and very very steady soldering iron grip!

Your idea of a resistor being broken/faulty might be right (which kind of makes sense) if you're getting higher than expected voltage readings. However, it's not easy to locate and keep in mind that accurate testing of a resistor while it's still connected to the circuitry and not isolated is not possible. You have to find the faulty resistor remove it from the pcb and then replace it with another one. This is where epic soldering skills come into play.

If you ask me it's not worth the hassle and 9 out of 10 times it can't be fixed, believe me I have tried. Then again it's not working and trying to fix an otherwise useless board wouldn't hurt. Good luck and update if you're actually able to fix it.
 
Feb 16, 2019
6
0
10
0
Just to make sure, by power on pins you mean the pins on the PSU 24-pin ATX12V connector? The green wire?

That (if possible) is the work of someone with hands-on experience with motherboard electronics and SMDs, nerves of steel and very very steady soldering iron grip!

Your idea of a resistor being broken/faulty might be right (which kind of makes sense) if you're getting higher than expected voltage readings. However, it's not easy to locate and keep in mind that accurate testing of a resistor while it's still connected to the circuitry and not isolated is not possible. You have to find the faulty resistor remove it from the pcb and then replace it with another one. This is where epic soldering skills come into play.

If you ask me it's not worth the hassle and 9 out of 10 times it can't be fixed, believe me I have tried. Then again it's not working and trying to fix an otherwise useless board wouldn't hurt. Good luck and update if you're actually able to fix it.
By the power pins i mean the ones one the motherboard, the JFP1 pins, i've read that they have to give me 3.3v and they dont.

I dont care too much if it is not fixable, at least i'll try and learn some soldering, professionals also start by not knowing so I think i'll give it a try :)
 

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