Thread: Looking for a creative solution: USB bus still powered after CPU is off

I "think" the hub is probably set up to open a set of contacts to keep the 5v supplies from fighting. Kinda like when you plug in a set of headphones to a headphone jack and it cuts off the speakers. This may not be true, but I would think they would have to. You may end up having to trim the 5v+ wire going to the usb. Here is a very (ready VERY!!!) basic drawing of how I would try hooking it up. I found a website with this info..."The maximum current the fan headers can provide is 0.5A. The maximum 12v fan power that the motherboard can support on each header is 6W"....which tells me a relay should be no sweat for it. But again, I would like to hear from the electronic guru's here to be safe.

Speed Racer

Could that be done with the main 12v line from the battery to the computer. Id much rather cut power there AND the USB hub power supply. How would i go about doing that?

Not sure that I follow completely. My idea was to use the fan header to turn off the power to the hub...are you asking about using the 12v to the board to kill the usb? in that case I would think so. If you want to cut all power on the 12v line to the pc, I would not recommend a relay, it will be huge and will be more difficult to wire up.

Originally Posted by S4Per

I'm starting to think about this, tell me if it makes sense:

The front USB ports are NOT integrated into the mobo, therfore they have an actual connector that plugs into the mobo. What if a relay of sorts was wired into the particular power line here on the connector, which would be triggered to turn the power off based on the PC being shut down?

?

Suppose it would work, but I dont think powering a relay off a usb port will be that good. I prefer the fan connector because it is made for higher current draws.

I think I may be misunderstanding you though. Are you trying to turn off the usb's or cut power to the whole system?

Personally I want to cut main power to the Opus after it has triggered the shutdown of the system so that the USB ports dont have power. I also want it to reset quicky so when i turn the car to ACC or further the computer comes on without having to push any buttons other than turning the key.