Desktop computer contains two main chips on motherboard. These two chips are called chip set. Chip near the processor socket is called North Bridge or Graphics and Memory controller HUB(GMCH) or System controller Hub. North Bridge mainly does processing and Display related job.If there is a no-disply problem in the motherboard, north bridge may be faulty. But other faulty components can cause the same problem. So, how do you confirm that north bridge is faulty?
Lets know the voltages comes to North Bridge
- Cpu vtt ( It is around 1.2 volt in old motherboard and 1.05 volt in latest boards). There is an dedicated switching mosfet set or single linear regulator to generate voltage. The input voltage voltage of this section comes from 3.3 volt orange wire of ATX power supply or Ram ram section or from chipset Vtt section.
- Ram operating voltage( Depends upon RAM generation) This voltage directly comes from RAM Vcc supply section.
- Chipset Vcc ( It is around 1.5 volt for old motherboard and 1.1 volt for latest motherboard) There is an dedicated switching mosfet set or single linear regulator to generate voltage. The input voltage voltage of this section comes from 3.3 volt orange wire of ATX power supply or Ram ram section
Steps to Diagnose
- If CPU fan is running and Other section is active but no display. RAM and North Bridge section may be faulty.
- Check ram and RAM power supply section including ram Vcc, RAM Vtt, SPDVtt signal Etc.
- If Ram section is OK, then check both CPU Vtt and Chipset Vcc.
- If you find any short in the section , try to figure out the faulty component
- try to check the components one by one by removing them from the PCB.
- After removing all components of both two section, if Short is till there it is confirm that the north Bridge itself is faulty.
Now, Replace the North Bridge using BGA machine.