Question what can cause a collapse in USB voltage?

Jun 3, 2019
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Hi everyone!

I have a Gigabyte GA-Z170X-Gaming 7 mainboard with a Corsair RM750i power supply. I was noticing the other day that my USB devices disconnect at random so I investigated a bit further. I measured the voltage at any given USB port which is 5.06V. However, when I'd connect a load (I used two different memory sticks as a sample) the voltage would collapse to just around 1.5V.

I'm not sure if this could be a PSU failure or a MoBo failure.

Would appreciate suggestions how to diagnose this further!
 

Eximo

Titan
Herald
That is odd, like a leak to ground. You must be getting proper 5V for normal operation elsewhere.

Disconnect all the USB ports on headers as a start. Test each port to see if it can narrowed down.

If it is the motherboard, you should probably pick up a Z270 board while they are still in stock.
 
Jun 3, 2019
2
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10
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Disconnect all the USB ports on headers as a start. Test each port to see if it can narrowed down.
I've disconnected everything and ran the board in a test-bench-like setup. The problem was still there. I'll try and borrow a PSU from a friend tomorrow to double check.

Well getting ahold of some schematics for the board would be great, but I doubt that's going to happen. I heard that there's an USB ESD protection chip on older gigabyte boards that's prone to failure.

If it is the motherboard, you should probably pick up a Z270 board while they are still in stock.
I'll try to do that then when nothing's going to help.
 

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