Possible noise on USB bus from console port?

Sharing an issue I’ve seen, not sure if it’s unique to my setup:

When I have the Ten64’s USB-C console port connected to my laptop’s (Dell Precision 3561) Thunderbolt port, I observe odd behavior with the USB HID devices connected to the second Thunderbolt port via a dock. I.e. jumpy mouse cursor (wireless mouse), previously I have seen errors with keyboard input (e.g. entry delays, reppppppppppppppppppeating characters), though I have not observed keyboard issues lately possibly due to a system board replacement, possibly due to a different Ten64 being used. Switching to a heavily shielded USB-C cable helped a bit, but did not eliminate the issue.

Not sure if the Ten64 is the source of the issue or if it’s a coincidence; I haven’t noticed it on other devices. Both the laptop and the Ten64 are connected to the same mains supply / ground source.

I know the console port is active when the Ten64 is powered off so it seems as if it sources its power from the laptop’s VBUS which is why I wondered if there’s an interaction somewhere.

If it is only wireless accessories affected, be aware USB (3) operates at a freuqency that can cause interference at 2.4GHz, so can induce quite some noise into that spectrum, which is used for Bluetooth and other wireless protocols. ( There is an entire document by Intel on how this works: https://www.usb.org/sites/default/files/327216.pdf )

If wired devices are also affected, of course this does not apply.

I would assume (and hope) the only VBUS usage on the Ten64 when it is off is to power the USB-UART converter chip, and other things being isolated from that, such that it should not cause any issues.

For clarification, the mouse is wireless (2.4 Logitech Unifying receiver) but the keyboard wired. Good to know and I considered the wireless an issue immediately; however, since I’ve seen it on wired as well thought it was worth sharing.

This may very well have been a Dell issue but just throwing it out there to see if anyone else has experienced this. I haven’t noticed the keyboard issue since I had the motherboard replaced (for other reasons).