Chassis fan failure causes no boot

A general-purpose computer uses a KT7 motherboard, which recently installed a chassis fan in the chassis because of the hot weather. After installation found unable to start the computer, power off automatically after the boot.

Analysis (1) According to the phenomenon of failure to first check the power supply error, the results indicate normal.

(2) With the suspected installation of the chassis fan encountered a certain board card so that the board card contact bad, after reseating a variety of cards, the fault remains.

(3) It is thought that the chassis fan is carefully inspected because of the failure of the newly added chassis fan. It turns out that the chassis fan is using a fake three-legged power connector, that is, the 3rd foot used to test the fan speed is not connected. Because the chassis fan power cable is relatively short, when the wiring is directly connected to the motherboard on the C fan connector, the original CPU fan connector connected to the S fan connector, and this section motherboard with automatic detection of CPU fan function.

(4) Because the chassis fan uses the fake three-pin power connector, the motherboard can not measure the speed of the fan after boot. In this way, the motherboard BIOS will assume that the fan does not turn, thus automatically start protection mode to cut off the power to protect the CPU is not burned, the above power-on start power failure.

After the elimination process determines the cause of the failure, the process of troubleshooting is as follows.

(1) Turn off the computer, unplug the power Plug and open the mainframe chassis.

(2) Connect the chassis fan to the S fan connector on the motherboard and connect the CPU fan back to the C fan connector. (3) Power on and reboot the system. All normal, troubleshooting.