Question Motherboard no POST after assembling chassis fan wrongly ?

Jun 28, 2021
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It is possible if I've assembly the chassis fan wrongly to the motherboard, it will cause the motherboard to be damaged?

Initially, there is a chassis fan which is connected to SYS_FAN3 via 3 pin connecter and I was able to boot the pc accordingly.

After that, I noticed that there are another 2 additional chassis fans which was not plugged in and I tried to stack the molex connecter to the fan which is currently connected to SYS_FAN3 as they have a splitter and tried to turn on the PC and it will not turn on anymore. There was no beep or lights on the motherboard however there is a light indication on the GPU still while it is connected to the motherboard.

What I've tried so far was :
  1. Paper clip test on the psu and it was working fine which eliminates faulty PSU
  2. I've tried to remove the ram and turn the power on but there was no beeps.
  3. I've tried to reseat the hardware except for CPU and turn it back on but it is still the same.
Would appreciate it if someone have any advise for me.
 

iPeekYou

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Jul 7, 2014
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It is possible if I've assembly the chassis fan wrongly to the motherboard, it will cause the motherboard to be damaged?

Initially, there is a chassis fan which is connected to SYS_FAN3 via 3 pin connecter and I was able to boot the pc accordingly.

After that, I noticed that there are another 2 additional chassis fans which was not plugged in and I tried to stack the molex connecter to the fan which is currently connected to SYS_FAN3 as they have a splitter and tried to turn on the PC and it will not turn on anymore. There was no beep or lights on the motherboard however there is a light indication on the GPU still while it is connected to the motherboard.

What I've tried so far was :
  1. Paper clip test on the psu and it was working fine which eliminates faulty PSU
  2. I've tried to remove the ram and turn the power on but there was no beeps.
  3. I've tried to reseat the hardware except for CPU and turn it back on but it is still the same.
Would appreciate it if someone have any advise for me.
High chance that the MB is fried, assuming you're still facing the symptoms after removing the offending fans. Molex is much higher than the PWM header rating at 4.5A vs 1A. We can't really be sure of what gets killed (if any) when something is shorted. I once did the same mistake that you did --tried to connect Molex connectors while the 3-pin connection is connected to a fan hub. Luckily, the only thing I killed was the fan itself. I did see sparks when connecting the Molex cables, making me realize it was a grave mistake.

Just keep in mind most 3-pin/Molex capable fans are made for one power source only --either full send through motherboard header (or fan hub, for that matter) or full send through Molex. 3-pin only fans may be controlled through motherboard reasonably since they tend to be simple no-frill fans starting at 5V as opposed to, say, LED fans that usually require 7V as starting voltage.
 
Jun 28, 2021
3
0
10
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High chance that the MB is fried, assuming you're still facing the symptoms after removing the offending fans. Molex is much higher than the PWM header rating at 4.5A vs 1A. We can't really be sure of what gets killed (if any) when something is shorted. I once did the same mistake that you did --tried to connect Molex connectors while the 3-pin connection is connected to a fan hub. Luckily, the only thing I killed was the fan itself. I did see sparks when connecting the Molex cables, making me realize it was a grave mistake.

Just keep in mind most 3-pin/Molex capable fans are made for one power source only --either full send through motherboard header (or fan hub, for that matter) or full send through Molex. 3-pin only fans may be controlled through motherboard reasonably since they tend to be simple no-frill fans starting at 5V as opposed to, say, LED fans that usually require 7V as starting voltage.
Thank you for the reply.

Well that was my suspicion as well that the mobo is fried at a certain area as the the GPU still have an led light when its plugged in and switch on.

I didn't think that the motherboard would be so fragile and I guess it's a lesson for me to learn.

I'll still try to reseat the CPU for 1 last attempt and hopefully that will work. Otherwise, it's gonna be a new mobo then.
 

iPeekYou

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Jul 7, 2014
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Thank you for the reply.

Well that was my suspicion as well that the mobo is fried at a certain area as the the GPU still have an led light when its plugged in and switch on.

I didn't think that the motherboard would be so fragile and I guess it's a lesson for me to learn.

I'll still try to reseat the CPU for 1 last attempt and hopefully that will work. Otherwise, it's gonna be a new mobo then.
Good luck, man. Dead motherboards can still provide power to components connected to it --to have them work properly is another story. My last dead board (MSI B75) had GPU light and fans on, likewise with any fans connected to the board. The board itself was toast.

Out of curiosity, what were the offending fans? I don't think many Molex/3-pin fans are still around, at least not from name brands.
 
Jun 28, 2021
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Good luck, man. Dead motherboards can still provide power to components connected to it --to have them work properly is another story. My last dead board (MSI B75) had GPU light and fans on, likewise with any fans connected to the board. The board itself was toast.

Out of curiosity, what were the offending fans? I don't think many Molex/3-pin fans are still around, at least not from name brands.
I see, thanks for the input. I guess I'll just try out to get a new motherboard then.

Anyway for the fan, I think it was from some cheap pc casing with Tecware brand and it was a casing I've gotten from 2 - 3 years ago which I did not make use of.
 

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