Several USB ports on my PC have gradually stopped working with devices that draw more power. My mouse, keyboard, and flash drive usually work, but two USB Wi-Fi adapters and an Xbox controller repeatedly connect and disconnect. Windows refreshes Device Manager during these cycles, and the same adapters work normally on another computer.
I tested both the rear USB 2.0 and USB 3.x ports. Some ports still recognize a mouse but not a flash drive, while neither Wi-Fi adapter works reliably on any port. This makes me wonder whether the USB ports are failing to provide enough power, or whether the problem is caused by the motherboard, USB controller, PSU, or Windows drivers.
The system uses an MSI MAG A550BN 550W 80+ Bronze power supply and an MSI B450M PRO-VDH MAX motherboard. What tests can determine whether the ports are delivering proper voltage and current, and is there anything I can try before buying a USB power meter or multimeter?
4 Answers
Try a powered USB hub as a diagnostic. If the Wi-Fi adapters and controller work reliably through a powered hub, the PC's port power delivery is suspicious. If they still disconnect, the issue may be data signaling, the USB controller, or the devices' cables rather than simply insufficient current. Avoid repeatedly using a visibly damaged or loose port, since a short or bent contact can trigger overcurrent protection.
A USB power meter would be a useful first check because it can show the port voltage and current while a device is connected. Test a known-good port and compare it with the failing ones. A port that drops voltage or repeatedly resets under load may have a damaged connector, protection circuit, or USB controller.
Before replacing hardware, try the basic software checks: remove the affected USB devices from Device Manager, reinstall the motherboard chipset and USB drivers, disable USB selective suspend in the power settings, and shut the PC down completely before disconnecting power for a few minutes. You can also boot from a Linux live USB; if the same devices repeatedly connect and disconnect there, Windows and its drivers are unlikely to be the cause.
The PSU is possible, but it is not the most likely explanation when the computer is otherwise stable and the graphics card is working normally. USB power comes from the PSU through the motherboard, so a motherboard USB power circuit, chipset, controller, or port protection circuit can fail independently. Since the problem appeared gradually across rear motherboard ports, the motherboard or its USB controller deserves serious consideration.
A PSU tester can check the main supply rails, but it usually will not directly prove whether the motherboard is supplying correct power to individual USB ports. A USB meter is more relevant for this particular symptom.
The failing devices work on another computer, while low-power devices still work on this one. I have not yet been able to measure the ports because I do not own a USB meter or multimeter.