Why USB device not recognized?

Free computer tip for USB

Sometimes it happens that you connect a USB device to your system and it shows "Unknown device". There may be several reasons for showing this.

Virus Infection:
First of all check that you system may not be infected with virus/spy ware/malware/adware because sometimes they also create problem for USB connectivity.

check USB connecting wires:
the front USB ports on your PC case may be misconnected. It's good to check the wire connections of USB port. The correct order of connection is Red, White, Green, and Black. only four wires are required per USB.

Device driver:
If windows is unable to recognize the device, try installing the driver yourself by inserting driver CD or windows CD. sometimes required drivers are not automatically installed on your system.

Power for device:
few devices require extra power to work properly, In this case if the USB is shared then it cannot provide required amount of power and device may not work.

Defective device:
You USB device may be defective. try using it on some other system.