AUTO POWER ON MOTHERBOARD
These is very rare problem, but when occurs its very frustrating.
As soon as the main AC power outlet is turned ON, the desktop starts running, without pressing POWER ON button of desktop.
REASON FOR THESE PROBLEM:----
1) Power ON switch pin could be ground.
2) Super IO chip is faulty.
Solutions:----
1) Clean the Pin with Cleaning solution.
2) Clean the Super IO chip pins with isoprophyll alcohol liquid.
If problem persists,then Super IO chip will need to be replaced.
Understand these problem:----
When power switch is short with ground ,+ 5 volt dropout is received at Super IO chip.
IO chip takes these dropout as a signal to start the motherboard.
In real when power button is pressed,the drop out is received at Super IO chip.But when power switch is short the signal directly goes to Super IO chip Pin without pressing Power-switch button.
See below Above is the track of Power flow for system Start up of Pc motherboard.
These is how the motherboard gets start.
The plus 5 volts from SMPS goes to the positive pin of Power switch button.When these button is pressed the plus 5 volt gets dropped and pass to the super IO chip and the system turns ON.
These is very rare problem, but when occurs its very frustrating.
As soon as the main AC power outlet is turned ON, the desktop starts running, without pressing POWER ON button of desktop.
REASON FOR THESE PROBLEM:----
1) Power ON switch pin could be ground.
2) Super IO chip is faulty.
Solutions:----
1) Clean the Pin with Cleaning solution.
2) Clean the Super IO chip pins with isoprophyll alcohol liquid.
If problem persists,then Super IO chip will need to be replaced.
Understand these problem:----
When power switch is short with ground ,+ 5 volt dropout is received at Super IO chip.
IO chip takes these dropout as a signal to start the motherboard.
In real when power button is pressed,the drop out is received at Super IO chip.But when power switch is short the signal directly goes to Super IO chip Pin without pressing Power-switch button.
See below Above is the track of Power flow for system Start up of Pc motherboard.
These details will help.
Thanks.
For more understanding on motherboard problems,go through the troubleshooting help links:-----
Troubleshoot Dead Motherboard
Troubleshooting NO Display
Problem on Motherboard
Troubleshooting CPU Overheating Problem on Motherboard
Desktop Motherboard Cpu Fan
Connector
No SMPS
Power Good on Super I/O Chip
MCH OR ICH Heating on Motherboard
