USB Hubs and Peripheral Power: Why Devices Disconnect, Drives Aren't Detected and Which Hub to Choose

Laptops keep getting thinner with fewer ports, while we keep getting more devices: a mouse, keyboard, external drive, printer, webcam, phone and flash drives. The obvious answer is a USB hub. But hubs are behind a lot of strange problems: an external drive disconnects by itself, the printer disappears from the system, Windows reports "USB device not recognised". Let's look at how USB hubs work, why these faults happen and how to choose a hub that won't cause trouble.

How a USB hub works

A hub turns one computer port into several. The key thing to understand is that all the devices on a hub share both the speed and the power of that one port. If you connect an external drive, a webcam and a flash drive to one port through a hub, they have to "share" — and when something runs short, one of the devices starts misbehaving.

Passive and powered hubs

• A passive hub (no separate power adapter) draws power only from the computer's port. It's enough for a mouse, keyboard, flash drives and other low-power devices.
• A powered hub (with its own adapter) gives every device enough current regardless of the computer. You need one for 2.5" external hard drives, several devices at once, and charging phones and tablets.

The most common reason external drives disconnect through a hub is a lack of power. A mechanical drive needs more current while spinning up than a passive hub can supply, especially if something else is connected too.

Speed: USB 2.0, 3.x and USB-C

Cheap hubs often use the USB 2.0 standard — up to 480 Mbit/s. That doesn't matter for a mouse and keyboard, but an external SSD on such a hub will run dozens of times slower than it could. USB 3.x hubs (usually blue ports or an SS marking) deliver 5–10 Gbit/s. USB-C is a connector shape, not a speed: a USB-C hub can be fast or slow, so check the stated standard.

Docking stations for laptops

A USB-C docking station is an advanced kind of hub: through a single cable it gives the laptop charging, a monitor connection, wired internet, audio and several USB ports. It's handy for a workspace: sit down, plug in one cable and everything works. But the laptop's port must support video output and charging over USB-C, and the dock's charging power must be enough for your laptop. There's more on the high-speed standards in our article on USB4 and Thunderbolt.

Common USB problems

• "USB device not recognised" — insufficient power, a bad cable, a faulty port or hub, or a driver glitch.
• An external drive keeps disconnecting — power, USB power saving in Windows, or a bad cable or hub.
• A device works in one port but not another — different controllers; front case ports are often wired with long leads and work worse than the rear ones.
• A wireless mouse or keyboard lags — radio interference from USB 3.0 ports and devices near the receiver.
• Devices disappear after sleep — Windows cuts power to USB ports to save energy.
• A port has stopped working altogether — physical damage to the connector or controller; that calls for a diagnosis.

USB power saving in Windows

By default Windows may switch off idle USB devices and ports to save energy. It's especially noticeable on laptops: an external drive "falls asleep" and doesn't wake, or a printer or scanner gets lost. These features are set in the power options and Device Manager, but they should be changed deliberately so you don't hurt the laptop's battery life.

Safety

Cheap no-name hubs and USB chargers sometimes have no overload or short-circuit protection. A faulty hub can damage the computer's port or a connected device. Also, don't plug found flash drives or unknown USB devices into a work computer: that's how viruses spread.

How to choose a hub

• For a mouse, keyboard and flash drives — a passive USB 3.0 hub from a well-known maker.
• For external drives and many devices — a powered hub with its own adapter.
• For a laptop workspace — a USB-C docking station compatible with your laptop.
• For an external SSD — connect it straight to a fast port on the computer, without a hub.

What our technician does

1. Diagnoses the cause of the faults: port, cable, hub, power or driver.
2. Checks the ports on your computer or laptop, including the front case connectors.
3. Selects a hub or docking station compatible with your device.
4. Sets up drivers and USB power-saving settings in Windows.
5. Organises your workspace: connecting monitors, drives, the printer and charging through a dock.

A real example

A photographer in Didube kept his photo archive on two external hard drives connected to his laptop through an inexpensive passive hub, along with a card reader and a mouse. The drives kept disconnecting in the middle of copying, and once Windows offered to format one of them. Our technician found that the drives weren't getting enough power, and Windows was also cutting power to the USB ports to save energy. We replaced the hub with a powered one, adjusted the power settings and checked the drives — fortunately, no data was lost. The disconnections stopped, and we recommended keeping a copy of the archive in the cloud.

Call a technician

If devices keep disconnecting or aren't detected, or you want a tidy, convenient workspace, we'll come to any district of Tbilisi around the clock. Learn more on our computer diagnostics, driver installation and computer setup pages.