How to fix Windows restart due to motherboard failure

The story :

This PC was returned from our construction site. The problem was that it is unstable. It shut down or reboot itself.


Specification :
- Pentium Dual Core
- Gigabyte G41 Combo Mainboard
- 2 GB RAM
- 500GB Hard  disk


How I check :

1. I tried testing with PC diagnostic tools (PC Doctor or BurnIn Test) but doesn't find any problem. 
2. I checked  Bios (press 'Del' when switch on power) and check the processor temperature. It is OK. 36 Celsius. (OK between 30 to 50 degree Celsius)
3. Check motherboard physically to see of the are any defective capacitor (leaking capacitor)

What I found :
Found leaking capacitor (see picture)

How I fix it :

1. Replace the motherboard with a new one.
2. Unless you're a trained technician, I don't recommend you changing the leaking capacitor yourself.

Additional note :

• There may be other component that may cause PC to reboot. Defective RAM and graphic card can be diagnosed with software testing tools such as PC Doctor or Passmark BurnIn Test.
• Replacing capacitor is dangerous as capacitor keep electrical charge even though the PC is turned off. Don't do it unless you're a professional.