F5F Stay Refreshed Hardware Desktop PSU not functioning, 24-pin cable missing pin 14—does the issue lie with the cable or the PSU?

PSU not functioning, 24-pin cable missing pin 14—does the issue lie with the cable or the PSU?

PSU not functioning, 24-pin cable missing pin 14—does the issue lie with the cable or the PSU?

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Paravichini
Junior Member
34
06-29-2025, 04:29 AM
#1
I'm working on my first PC and encountered problems with power and unsure if the issue lies with me or a component. I've connected everything for testing, but the PSU won't even start. During the paper clip test it briefly powered on and then shut off. When checking the parts, the cable seems to be missing a pin I expect to be present, but I'm not familiar with pin 14 being absent. Is this normal or is there something I'm missing? Anyone have any advice or know what might be going wrong?
P
Paravichini
06-29-2025, 04:29 AM #1

I'm working on my first PC and encountered problems with power and unsure if the issue lies with me or a component. I've connected everything for testing, but the PSU won't even start. During the paper clip test it briefly powered on and then shut off. When checking the parts, the cable seems to be missing a pin I expect to be present, but I'm not familiar with pin 14 being absent. Is this normal or is there something I'm missing? Anyone have any advice or know what might be going wrong?

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trozenn
Junior Member
30
06-30-2025, 01:16 AM
#2
The missing pin is typical. It previously provided -5V, but today's computer power supplies no longer need this because modern parts don't require it. If you're looking at the second position from the top left in your image, there should be a pin there, though it shouldn't interfere with the power supply or computer functioning. This pin is for -12V, which is reserved for serial ports, and it's unlikely that motherboards verify its presence. It's possible the COM header is no longer present to connect a serial port adapter.
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trozenn
06-30-2025, 01:16 AM #2

The missing pin is typical. It previously provided -5V, but today's computer power supplies no longer need this because modern parts don't require it. If you're looking at the second position from the top left in your image, there should be a pin there, though it shouldn't interfere with the power supply or computer functioning. This pin is for -12V, which is reserved for serial ports, and it's unlikely that motherboards verify its presence. It's possible the COM header is no longer present to connect a serial port adapter.

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_DarkStone_
Member
227
07-06-2025, 06:36 PM
#3
It looks like your PSU operates in a semi-passive mode with no fans running under light load. You don’t need to halt there. Updated on December 29, 2023 by leclod
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_DarkStone_
07-06-2025, 06:36 PM #3

It looks like your PSU operates in a semi-passive mode with no fans running under light load. You don’t need to halt there. Updated on December 29, 2023 by leclod

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AER0D
Member
55
07-06-2025, 08:17 PM
#4
some power supplies remove the -12v rail due to budget constraints, similar to the -5v rail; it’s no longer needed.
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AER0D
07-06-2025, 08:17 PM #4

some power supplies remove the -12v rail due to budget constraints, similar to the -5v rail; it’s no longer needed.

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fantasy_miner
Member
166
07-06-2025, 10:01 PM
#5
I didn't realize the second pin was redundant, so I won't be concerned about it. Any suggestions for the PSU? Thanks!
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fantasy_miner
07-06-2025, 10:01 PM #5

I didn't realize the second pin was redundant, so I won't be concerned about it. Any suggestions for the PSU? Thanks!

C
61
07-06-2025, 11:32 PM
#6
It might be due to limited understanding, but there are ways to confirm everything functions properly during your motherboard and connection tests. If nothing appears to activate, check the connections carefully and ensure all components are properly seated.
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ChickenisBeast
07-06-2025, 11:32 PM #6

It might be due to limited understanding, but there are ways to confirm everything functions properly during your motherboard and connection tests. If nothing appears to activate, check the connections carefully and ensure all components are properly seated.

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173
07-07-2025, 04:53 AM
#7
I know what you mean. Thanks for your help!
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firebuckler123
07-07-2025, 04:53 AM #7

I know what you mean. Thanks for your help!