I have an external PCIE->TB3 device paired with the Intel NUC7i5BNH with W10. When I power off the NUC the external device's PSU is still active and the fans are relatively loud. When I disconnect the USB connection between the devices, the fans shut down. This makes me think that there might be a way to treat the device as not present or not connected when in the sleep or powered off state.I've looked in the BIOS and switched the USB power to OFF but that didn't do anything.
I haven't done much further research on this, so my main question is whether it is possible and how?
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This is expected behavior. USB power will be provided by the USB port even if the unit is powered off. In BIOS, you can enable or disable Portable Device Charging Mode, but it will cause the unit to either provide extra power during S4/S5 sleep states or not.
In this case, you need to unplug external devices to turn them off completely.
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