Hi
mccmw,
Yes, this is a reasonable place to ask it.
What you’re describing does
not sound like a normal Windows “setting” issue. Because it happens when the
USB-C plug is only just touching the port, the most likely cause is
electrical interference, not software.
What is probably happening
When the USB-C shell gets close to or first touches the hub, one of these usually happens:
- Ground equalization / tiny discharge
- The hub, PC, monitor, and power adapter may be sitting at slightly different ground potentials.
- The moment the connector shell touches, that difference equalizes.
- That brief transient can disturb the HDMI link long enough for the monitor to think the signal disappeared.
- EMI / shielding problem
- USB 3.x devices and hubs can generate a lot of high-frequency noise.
- If the hub or HDMI cable shielding is weak, the HDMI signal can drop for a moment.
- The monitor then goes black or enters sleep because it briefly loses sync.
- Hub hardware or power design issue
- Some hubs are just poorly designed.
- An externally powered hub with marginal grounding or filtering can cause odd behavior exactly like this.
The key clue is this:
- If the monitor blanks before the device is fully inserted, Windows is probably not the trigger.
- That points to hardware-level electrical noise, grounding, or cable shielding.
Most likely fixes
Try these in order, from easiest to most useful.
1. Move the hub away from the HDMI cable and monitor cable
- Place the hub as far from the HDMI cable and monitor as practical.
- Make sure the USB-C plug and hub are not physically brushing the HDMI cable.
- Test again.
If this helps, the problem is likely
EMI coupling.
2. Try a different HDMI cable
- Replace the HDMI cable with a shorter, better-shielded one.
- If you have one, use a cable with ferrite chokes.
- Test the same USB-C connection again.
A weak HDMI cable is a very common cause of brief signal dropouts.
3. Plug the hub power adapter and monitor into the same power strip
- Shut everything down.
- Plug the PC, monitor, and hub power brick into the same surge protector/power strip.
- Power back on and test.
This can reduce
ground potential differences between devices.
4. Test a different USB port path
- Connect the hub to a different USB port on the PC.
- If possible, try a rear motherboard port instead of a front-panel port.
- Test again.
Front-panel ports and some internal headers are more susceptible to grounding/noise issues.
5. Try the monitor on a different input
- If your monitor and PC support it, test with DisplayPort instead of HDMI.
- If not, try another HDMI input on the monitor.
- Test the hub again.
DisplayPort sometimes tolerates this kind of disturbance better than HDMI on a given setup.
6. Disconnect the hub’s AC adapter briefly and test
- Power off the hub if needed.
- Disconnect the hub’s external power supply.
- Test with a low-power USB device only.
- Do not do this with devices that need the hub’s external power.
If the behavior changes, the external power supply or grounding through it is likely involved.
7. Try a different USB-C cable/device
- Test with another USB-C cable.
- Test with another USB-C device.
- See whether the screen blanks with every device or only one.
If it only happens with one cable/device, that cable or device may be leaking noise into the connection.
Windows settings to check
Because this happens on
near contact, I would treat Windows as a secondary suspect. Still, you can try these:
1. Disable USB selective suspend
- Open Control Panel.
- Go to Power Options.
- Click Change plan settings.
- Click Change advanced power settings.
- Expand USB settings.
- Set USB selective suspend setting to Disabled.
- Restart and test.
2. Update GPU and chipset drivers
- Install the latest graphics driver from NVIDIA, AMD, or Intel.
- Install the latest motherboard chipset/USB drivers from your system or board vendor.
- Restart and test.
This may help if the HDMI link recovery is overly sensitive, but again it probably will not fix the root cause if the issue happens at first touch.
What I suspect most
My best guess is:
- A grounding or ESD transient from the powered USB hub
- Combined with
- An HDMI link that is sensitive to a momentary disturbance
So I would focus first on:
- Same power strip for all devices
- Better / shorter HDMI cable
- Greater physical separation between hub and video cabling
- Testing another hub or another power adapter if available
Strong clue: this may be a hub quality issue
If none of the above changes anything, the hub itself may simply be the culprit.
A good test is:
- Borrow or try another externally powered USB-C/USB 3.x hub.
- Recreate the same setup.
- If the monitor no longer blanks, your current hub is almost certainly the cause.
What to report back
If you want, reply with these details and I can narrow it down further:
- Your PC or motherboard model
- Your monitor model
- Whether the display is connected by HDMI directly from the GPU or from the motherboard
- The brand/model of the USB hub
- Whether this happens with all USB-C devices or just one
- Whether it still happens if the hub’s power brick is unplugged
At the moment, though, I would
not call this a Windows bug first. It sounds much more like a
hardware interference/grounding issue.
If not, let me know and I'll try to move or re-post. I have a USB 3.1 Gen 2 Hub with 6 Type A and 4 Type C ports. It is externally powered (AC adapter). For some reason, when a Type C connector is about to be connected (almost or just touching but not inserted yet), it triggers my HDMI monitor to "sleep." Movement of the mouse turns it back on, and the USB device usually connects properly. I've never encountered this behavior before. 
