5 reasons for not recognizing usb device under Windows 7 Ultimate system

1. Do not pull out the USB read/write device. Otherwise, the device may be burned out. The USB device amount icon in the win7 system task bar will open the icon. The U disk device will be displayed in the list, and it is safer to choose to deactivate the device and then unplug the device.
2. It may be that the USB interface voltage is not enough. When the mobile hard disk is connected to the front USB port, the system may fail to recognize the device fault. Because the power of the mobile hard disk is relatively large, the voltage is relatively strict, and the front interface may not provide sufficient voltage. Of course, the inferior power supply is also This may cause this problem. Solution: Do not connect the mobile hard disk to the front USB port, replace the inferior low-power power supply or use the hard disk box of the external power supply.
3, motherboard and system compatibility issues, the most famous is the NF2 motherboard and USBde compatibility issues. If you encounter this problem on the NF2de motherboard, you can install the latest denForce2 dedicated USB2.0 driver and patch, the latest motherboard patch and operating system patch, or you can try to refresh the motherboard deBIOS.
4, system or BIOS problems, when you disable USB in the BIOS or operating system, it will happen that the USB device can not be recognized in the system. The solution is to turn on the option associated with the USB device. Press the F2 or DEL button to enter the BIOS and enable the enable usb device.
5, the front USB cable is not connected correctly. When the deUSB cable on the motherboard and the front USB interface on the chassis are connected, the fault will occur when the positive and negative terminals are reversed, because the positive and negative connections may cause the USB device to burn out. So try to use the chassis rear deUSB interface, and also use less extension cords. It may also be a problem with the fracture, change the USB port to see.
Also note: you should choose FAT when formatting under WINDOWS, do not choose FAT32.