USB Over current Error - Fixed.. I hope

[Pr0fPyr0]

I'm posting this since for two reasons 1. it might help someone else with this issue since I found plenty of internet posts with this same problem ; 2. Is this a fluke coincidence or did the oil become conductive.

 

So here's the story , 2 days ago I wake my PC from sleep and get a USB over current warning in windows, I start plugging things out and in nothing changes so I try a restart , that then stopped me from posting since I got the USB over current warning straight from the BIOS.

 

I proceed to start troubleshooting , checks all the ports , unplug everything , eventually the MB (MSI B450 Tomahawk) is outside on the table with only a GPU , CPU and RAM.. No luck, I don't have a spares to test with so I pop over the next day to a local repair shop and ask the guy to just slap a GPU on the board and a PSU so I know its not my PSU that's wrecked, same error.

 

At this point I have resided myself to a 98% chance that its a wrecked MB, still paranoid about other parts but I'm not going to pay 1/3 of a new B550 MB price to have some place do diagnostics when in all likely hood its just the MB, At this point I'm reminded how much it sucks to have knowledge but no tools to just swap and check stuff.

 

A day later shopping for boards once thing is still bothering me a random seemingly unlikely theory I had, I noticed the back of the MB PCB was darker at the VRM cooling areas , I know the thermal pads can seep oil and that can then leech into the board but its non-conductive, but what if over time it became just conductive enough from ions, dust or whatever to cause an issue , so I removed the VRM heat sink closest to the back plate and cleaned the MOSFET area with some cotton buds on alcohol... IT POSTS , after some back wrenching reassembly and stress testing so far so good, will see for how long, its day 2 at time of posting.

 

Now I'm curious anyone else ever seen something like this , any ideas if its even possible that the oil became conductive or is it a coincidence ?

 

TLDR: If you get a USB over current warning and have tried everything , check if you have any VRM Thermal pad oil seepage that is causing a short.

 

 

[Isuck Assimov]

maybe the thermal conductivity of the oil residue could have added to the problem ?

Would make sense if the MB is calculating USB current draw with a thermocouple or something similar i guess.

[Pr0fPyr0]

40 minutes ago, Isuck Assimov said:

maybe the thermal conductivity of the oil residue could have added to the problem ?

Would make sense if the MB is calculating USB current draw with a thermocouple or something similar i guess.

From what I understand , there is an OCP IC that monitors voltage to the USB from the MOSFET's , my assumption is that something was shorting/bridging there

[Isuck Assimov]

interesting issue and fix for sure. Maybe LTT Labs could look into this and test different mobos and thermal pads for creeping conductivity