Causes
- The USB ports are downstream ports needing an 'upstream' link — the VG27AQ's two USB 3.0 ports act as a hub through the monitor: they only work when the monitor is connected to the computer with the included USB-B (upstream) cable, which is a separate cable from the DisplayPort/HDMI video link. Many owners never attach that USB-B cable, so the monitor's USB ports do nothing even though the picture is fine — this is the single most common reason.
- A loose, missing, or low-quality upstream cable — if the USB-B cable is plugged into only one end, is damaged, too long, or is plugged into a USB power/data port that cannot supply data, the hub enumerates intermittently or not at all, which reads as dead USB ports.
- A USB-B port on the monitor that is plugged into the computer's charge-only socket — plugging the upstream cable into a charge-only USB port, a powered USB hub's passthrough, or a port disabled in BIOS prevents data transfer even though the connection looks fine.
- Windows not installing or losing the hub driver — the monitor's hub enumerates as a "USB 2.0/3.0 Hub" under a standard driver, but a stale or corrupted USB driver stack, or a system that is mid-update, can cause Windows to show an unknown device or a failed hub and the SATA/USB attached devices to not appear.
- A power or port fault in the hub itself — like any hub, the VG27AQ's USB controller can fail on one or both ports, or its own power feed can sag so attached devices don't initialize — the least common but real cause, and the one that needs a warranty path to resolve.
How to Fix
- Connect the USB-B upstream cable — plug the included (or any standard) USB 3.0 type-B cable into the monitor's square USB-B "upstream" port (next to the USB 3.0 ports) and into a proper data USB port on the computer. Until that cable is in place, the VG27AQ's USB 3.0 ports are intentionally non-functional by design — this step alone resolves most reports.
- Verify the correct upstream/computer port — plug the upstream cable into a real USB data port on the motherboard (a rear-panel USB 3.0 socket is best). Avoid charge-only sockets and pass-through ports on low-end hubs. If your keyboard/mouse work elsewhere but not in the monitor's USB ports, check that the devices are powered and the upstream cable is seated firmly at both ends.
- Refresh the connection and test with a known-good device — reseat the upstream cable at both ends, then plug a simple device (a flash drive) into each monitor USB port. If the drive is detected, the hub works and the port/cable was the issue. If not, move the upstream cable to a second computer port and test again to separate a bad cable from a bad monitor port.
- Update/repair the hub driver in Windows — open Device Manager, expand Universal Serial Bus controllers and look for the monitor's hub (often listed as a "Generic USB Hub"). Right-click it → Update driver, or uninstall it and let Windows re-detect it, then restart. If the hub shows an unknown/yellow-bang device, run Windows Update and re-connect the upstream cable.
- Power-cycle the monitor and reset the OSD — unplug the VG27AQ from the wall for 30 seconds (this also resets the hub's power feed) and replug. From the OSD, check Set Up → USB or similar options for the correct USB mode, and do a factory reset if the ports were working before and stopped to clear any stuck hub state.
- Test each port and pursue warranty if one is truly dead — if both the upstream cable and a direct USB data port are confirmed working but neither monitor USB port detects anything, the hub board inside is likely faulty. Contact ASUS support under the display's warranty for a replacement — the USB hub is not user-serviceable.