F5F Stay Refreshed Hardware Desktop ATX-12V pins for ground connection

ATX-12V pins for ground connection

ATX-12V pins for ground connection

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Benny_Boy679
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217
03-27-2019, 07:05 AM
#1
Hi there, I haven’t worked on any PC parts in a long time and was thrilled when a friend came over with her gaming PC that wouldn’t power on after years of use. I began troubleshooting and, after disconnecting everything, used a continuity tester which showed a short circuit across all eight pins on the CPU power connector (on the motherboard side). This short disappears once the CPU is removed. I expected this to mean the CPU was dead, but I’m trying to eliminate the chance it’s the motherboard that’s failed. I can’t see any obvious damage to the VRMs. Do you have any experience with similar problems and know what might be wrong? I strongly think the CPU is the culprit, though I’m surprised it would fail in this way. Unfortunately, I don’t have any reliable hardware to test against, so I’m not entirely sure. Also, could this short have affected the power supply unit? I did a quick check outside the PC, and it can run some fans, with voltages looking normal. Thanks for your help—helping young gamers is what I’m here for! Hardware: Gigabyte B450 AORUS Pro Ryzen 5 3600 Some or another BeQuiet 600W PSU
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Benny_Boy679
03-27-2019, 07:05 AM #1

Hi there, I haven’t worked on any PC parts in a long time and was thrilled when a friend came over with her gaming PC that wouldn’t power on after years of use. I began troubleshooting and, after disconnecting everything, used a continuity tester which showed a short circuit across all eight pins on the CPU power connector (on the motherboard side). This short disappears once the CPU is removed. I expected this to mean the CPU was dead, but I’m trying to eliminate the chance it’s the motherboard that’s failed. I can’t see any obvious damage to the VRMs. Do you have any experience with similar problems and know what might be wrong? I strongly think the CPU is the culprit, though I’m surprised it would fail in this way. Unfortunately, I don’t have any reliable hardware to test against, so I’m not entirely sure. Also, could this short have affected the power supply unit? I did a quick check outside the PC, and it can run some fans, with voltages looking normal. Thanks for your help—helping young gamers is what I’m here for! Hardware: Gigabyte B450 AORUS Pro Ryzen 5 3600 Some or another BeQuiet 600W PSU

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Appri
Junior Member
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03-27-2019, 03:59 PM
#2
It seems the motherboard might be failing and the CPU could be dead as well. CPUs are built to have minimal resistance between their VIN and ground. Based on your measurement across the 12V, a high side MOSFET likely failed. To verify, test the resistance from the EPS power connector to the inductors—low resistance indicates a dead MOSFET.
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Appri
03-27-2019, 03:59 PM #2

It seems the motherboard might be failing and the CPU could be dead as well. CPUs are built to have minimal resistance between their VIN and ground. Based on your measurement across the 12V, a high side MOSFET likely failed. To verify, test the resistance from the EPS power connector to the inductors—low resistance indicates a dead MOSFET.

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Puppzi
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209
03-27-2019, 08:22 PM
#3
I understand your confusion about the inductors. It sounds like you checked their resistance across the highlighted areas on the board, assuming they were measuring ~4 ohms with the CPU connected. Is that considered acceptable for your setup?
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Puppzi
03-27-2019, 08:22 PM #3

I understand your confusion about the inductors. It sounds like you checked their resistance across the highlighted areas on the board, assuming they were measuring ~4 ohms with the CPU connected. Is that considered acceptable for your setup?

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Amegahoney
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03-30-2019, 07:17 AM
#4
You checked my request and confirmed the issue. The reading of 4 ohms is too low, indicating likely a failed MOSFET. Based on typical values, it should be several kiloohms, suggesting a short-circuit occurred. To identify the faulty component, you can desolder inductors until the issue resolves or test the board with power and observe which part heats up—using a thermal camera or applying isopropyl to see which evaporates faster. In practice, this isn’t a costly board, so unless you’re experienced, it’s probably not worth fixing. Please let me know when you’re ready to proceed.
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Amegahoney
03-30-2019, 07:17 AM #4

You checked my request and confirmed the issue. The reading of 4 ohms is too low, indicating likely a failed MOSFET. Based on typical values, it should be several kiloohms, suggesting a short-circuit occurred. To identify the faulty component, you can desolder inductors until the issue resolves or test the board with power and observe which part heats up—using a thermal camera or applying isopropyl to see which evaporates faster. In practice, this isn’t a costly board, so unless you’re experienced, it’s probably not worth fixing. Please let me know when you’re ready to proceed.

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CreeperChaos
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03-30-2019, 07:59 AM
#5
Thanks a lot for your assistance and the suggestion to reference! I won’t be replacing parts on this board. I’ll look for a different one instead.
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CreeperChaos
03-30-2019, 07:59 AM #5

Thanks a lot for your assistance and the suggestion to reference! I won’t be replacing parts on this board. I’ll look for a different one instead.

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