# "USB overvoltage" mobo dead?



## erixx (Dec 29, 2014)

Dear TPU'ers,
I wish to share an unlucky event, for those curious and maybe in the hope of someone understanding this.

After reading some guides I did not progress and consider my Asus Maximus VII Gene dead.

I left for dinner, with a game in it's menu screen, a joystick, a mouse and keyboard, printers, UPS, phone plugged into USB ports. plus a LED headlight for my mountainbike that charges over USB, it was the first time I charged it.

When I returned the PC was locked and screen dark, so I hard resetted it.

After several attemps, a BIOS screen came up, saying USB OVervoltage, will reboot in 15 seconds.

I have performed all tests of all USB ports, un pluging all irrelevant stuff, HDD's, well, all, and I always boot either in
Black screen
UEFI screen with ROG logo and "Press DEL or F2"
or abovementioned warning USB Overvoltage.

In all cases, nothing happens, I cannot boot, get into UEFI BIOS, or use keyboards of varied types.
I have no PS2 keyboard but used an kb-adapter.
Only once, after flashing the UEFI BIOS with a pendrive (with Asus hardware buttons and PC turned off) it went straight into the UEFI, but I could not navigate it.

Anyway, 9 times out of 10, no keyboard lights turn on at boot, so no F2 or DEL works.

6 months old mobo. The mobo I liked most in my life is dead... 
Tomorrow I will return it to seller and possibly get a Sabertooth Z97 Mark1.

Still I'd like to UNDERSTAND. Overvoltage? That is USB "feeding" electricity to the mobo, right? WEIRD.


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## OneMoar (Dec 29, 2014)

The over-voltage actually means over-current 
usually thats caused by either a short in the boards usb ports or in the case headers


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## erixx (Dec 29, 2014)

Thanks OneMoar, that is absolutly correct, seems to me! Yet, a short in ports or headers seems strange to me. I left and it was okay, I return to my computer room and the lights of devices were happily all on, blinking while charging etc... Then after a while it died. I heavily suspect the USB charging of the bicycle light (made in China, but what's not!) But HOW a device (non powered) can bring a mobo to it's knees!!!!????


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## Vario (Dec 29, 2014)

current draw


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## silkstone (Dec 30, 2014)

Vario said:


> current draw



I'm pretty sure USB standards require some sort of over current protection. So, if the port is only able to supply 1.5A, that's all it will give out, independent of the resistance of the preferential connected.


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## OneMoar (Dec 30, 2014)

silkstone said:


> I'm pretty sure USB standards require some sort of over current protection. So, if the port is only able to supply 1.5A, that's all it will give out, independent of the resistance of the preferential connected.


unless there is a short ......


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## xvi (Dec 30, 2014)

The bicycle light probably pulled more power than it should have. Was it plugged in to the back?
I thought 5v comes straight off the PSU.


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## silkstone (Dec 30, 2014)

OneMoar said:


> unless there is a short ......



That's the main point of having OCP. I know computer PSUs will have OCP; they are good to use in labs where you want to set up magnetic fields because even when you short the terminals, they will only every allow a certain current to flow.
I looked at the specs for USB 2.0 and 3.0 and noticed an OCP pin, not sure how it works exactly though and I've only found vague references to OCP in my 5 minutes of searching.


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## Mussels (Dec 30, 2014)

xvi said:


> The bicycle light probably pulled more power than it should have. Was it plugged in to the back?
> I thought 5v comes straight off the PSU.



if the PC is off or sleeping it can come from 5VSB, which can damage some PSU's


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## erixx (Jan 2, 2015)

I am bashing my head against a wall, but after ordering and installing a new mobo I had the same problem, until I simply "touched" wires in the case, seems like they auto-dis-shortened.... I thought it was a buggy DVD-power cable, but I connected it again later and all works fine....
Now I have a working Maximus 7 Gene and a new Sabertooth z97...  great! : )


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## OneMoar (Jan 2, 2015)

erixx said:


> I am bashing my head against a wall, but after ordering and installing a new mobo I had the same problem, until I simply "touched" wires in the case, seems like they auto-dis-shortened.... I thought it was a buggy DVD-power cable, but I connected it again later and all works fine....
> Now I have a working Maximus 7 Gene and a new Sabertooth z97...  great! : )
> View attachment 61287


short in one of the cables I would find out which ...


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## Mussels (Jan 3, 2015)

if it was USB, its gotta be 5V or 5VSB, possibly to ground.

fan adaptors and fan controllers that run off the 5V line can do this too, my PC wouldnt wake from sleep mode due to a 7V fan adaptor that bridged 5V and 12V to make 7V - the 5V SB couldnt handle 4x120mm fans off the adaptor, and would insta reboot.


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