Patent ID: 7512818

Claim:
A circuit for protecting a motherboard of a computer, a CPU with a CPU voltage terminal configured for electrically connecting to a power supply being mounted on the motherboard, comprising: a first transistor, a gate of the first transistor being connected to the CPU voltage terminal, a source of the first transistor being connected to ground; and a second transistor, a gate of the second transistor being connected to a drain of the first transistor through a node, the node being at low level when the computer is off, a drain of the second transistor being connected to a control signal terminal of the computer which acts to change the work condition of the computer, wherein when the computer is turned on and the CPU voltage terminal is not electrically connected to the power supply, the CPU voltage terminal is at low level to keep the first transistor turning off and the second transistor turning on, the control signal terminal turns to low level from high level to turn off the computer.