[SOLVED] Fried something when I used a broken USB port, now won't boot with 2 diff motherboards

May 21, 2020
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Hey everyone,

My new-ish PC has been working perfectly for 6 months or so, but recently froze and now won't POST. The CPU diagnostic light on the motherboard is lit up, and I'm having trouble finding the source of the problem.

This all started when I pulled a USB 3 (type A) cable out of its connector on the front of my case, and the guts of the connector came out with the cable. I very stupidly plugged a different USB cable into the broken connector, which continued to work for a day or two. At some point, however, the PC froze, and has been unable to boot since. Everything lights up, fans spin, etc, but no POST. My guess is that using the broken USB port fried a different component.

I immediately disconnected the USB3 connector from the motherboard, and it still wouldn't boot. I re-seated the CPU with no luck, then replaced it with a different CPU. I got the same result both times, and no pins appear to be bent on either CPU. So I did a motherboard bench test, pulling all components except the CPU, and even with no RAM, the CPU diagnostic light stayed lit. Replaced the motherboard with a different board, put all components back in (except the broken USB3 connector), and the PC still won't POST. Now the BOOT light is lit up on the new motherboard. There have been no issues with my OS hard drive at any point, any I've tried multiple SATA ports.

From my research here, I'm assuming this is likely a power supply issue? Would the paperclip test reveal the problem here, or should I try something else? I use the PC for my freelance work, so I'm trying to get back up and running as quickly as I can.

Here's my parts list:
PCPartPicker Part List: https://pcpartpicker.com/list/tttz9N

CPU: Intel Core i9-9900K 3.6 GHz 8-Core Processor
CPU Cooler: Scythe Mugen 5 Rev. B 51.17 CFM CPU Cooler
Motherboard: MSI MPG Z390 GAMING EDGE AC ATX LGA1151
Memory: G.Skill Ripjaws V Series 32 GB (4 x 16 GB) DDR4-3200 CL16 Memory
Storage: PNY CS900 500 GB 2.5" Solid State Drive
Storage: Samsung 970 EVO Plus 2 TB M.2-2280 NVME Solid State Drive
Storage: Seagate Barracuda Compute 2 TB 3.5" 7200RPM Internal Hard Drive
Storage: Seagate BarraCuda Pro 10 TB 3.5" 7200RPM Internal Hard Drive
Video Card: Gigabyte GeForce GTX 1650 SUPER 4 GB WINDFORCE OC Video Card
Case: NZXT H510i ATX Mid Tower Case
Power Supply: Thermaltake Smart 600 W 80+ Certified ATX Power Supply
Custom: Elgato Game Capture HD60 Pro, stream and record in 1080p60, superior low latency technology, H.264 hardware encoding, PCIe (x2)



Thanks so much for your help.
 

LinuxDevice

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May 20, 2017
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Can't answer your problem, but normally USB is "short tolerant" in the sense that if power is shorted from the USB delivery a fuse will temporarily remove power, and then later restore itself. What this won't help you with is if power went into some other wire (e.g., data +/-) and actually blew something out. If this were the case, then the motherboard itself would have issues. Whether such issues would completely stop boot I don't know, but it is likely boot could still work if you were to reset BIOS. Maybe.

The power delivery to a USB port is so small that the power supply itself would be at no risk from total current. What could happen is that spikes could be generated which could harm the power rails inside the motherboard. If you've tried a new motherboard though, perhaps it is some other component that died from a spike.

I would recommend disconnecting everything you can...leave out the hard drive, use only one stick of RAM, perhaps only use a keyboard on one of the integrated USB connectors, and see if it can at least POST.
 
Reactions: neonplants

LinuxDevice

Reputable
May 20, 2017
485
33
4,990
75
Can't answer your problem, but normally USB is "short tolerant" in the sense that if power is shorted from the USB delivery a fuse will temporarily remove power, and then later restore itself. What this won't help you with is if power went into some other wire (e.g., data +/-) and actually blew something out. If this were the case, then the motherboard itself would have issues. Whether such issues would completely stop boot I don't know, but it is likely boot could still work if you were to reset BIOS. Maybe.

The power delivery to a USB port is so small that the power supply itself would be at no risk from total current. What could happen is that spikes could be generated which could harm the power rails inside the motherboard. If you've tried a new motherboard though, perhaps it is some other component that died from a spike.

I would recommend disconnecting everything you can...leave out the hard drive, use only one stick of RAM, perhaps only use a keyboard on one of the integrated USB connectors, and see if it can at least POST.
 
Reactions: neonplants
May 21, 2020
12
0
10
0
Can't answer your problem, but normally USB is "short tolerant" in the sense that if power is shorted from the USB delivery a fuse will temporarily remove power, and then later restore itself. What this won't help you with is if power went into some other wire (e.g., data +/-) and actually blew something out. If this were the case, then the motherboard itself would have issues. Whether such issues would completely stop boot I don't know, but it is likely boot could still work if you were to reset BIOS. Maybe.

The power delivery to a USB port is so small that the power supply itself would be at no risk from total current. What could happen is that spikes could be generated which could harm the power rails inside the motherboard. If you've tried a new motherboard though, perhaps it is some other component that died from a spike.

I would recommend disconnecting everything you can...leave out the hard drive, use only one stick of RAM, perhaps only use a keyboard on one of the integrated USB connectors, and see if it can at least POST.
This solved it for me! Thanks for moving me away from thinking it was the PSU. I went down to one stick of RAM, booted into the BIOS of the new mobo, got some kind of weird error about wrong settings and fixed it there. Eventually got all components back in and working, albeit with a new motherboard. Thanks again.
 

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