Concept of PCH and No Display Problem

Concept of PCH   ( Platform Controller Hub )

1.Northbridge+Southbride+Graphics controller
2.( Northbridge+Graphics controller )+Southbride
3.( Northbridge+Southbride )  + Graphics controller
                    ⇓
                 PCH


ICH  ( I/O Controller Hub )  ( AMD -  FCH )
                   ⇓
          Southbridge 

I/O Controller Hub (ICH) is a family of Intel southbridge microchips used to manage data communications between a CPU and a motherboard, specifically Intel chipsets based on the Intel Hub Architecture. It is designed to be paired with a second support chip known as a northbridge. As with any other southbridge, the ICH is used to connect and control peripheral devices.

As CPU speeds increased data transmission between the CPU and support chipset, the support chipset eventually emerged as a bottleneck between the processor and the motherboard. Accordingly, starting with the Intel 5 Series, a new architecture was used that incorporated some functions of the traditional north and south bridge chips onto the CPU itself, with the remaining functions being consolidated into a single Platform Controller Hub (PCH). This replaces the traditional two chip setup.

 (GMCH) 

The northbridge typically handles communications among the CPU, in some cases RAM, and PCI Express (or AGP) video cards, and the southbridge. Some northbridges also contain integrated video controllers, also known as a Graphics and Memory Controller Hub (GMCH) in Intel systems. Because different processors and RAM require different signaling, a given northbridge will typically work with only one or two classes of CPUs and generally only one type of RAM.

There are a few chipsets that support two types of RAM (generally these are available when there is a shift to a new standard). For example, the northbridge from the Nvidia nForce2 chipset will only work with Socket A processors combined with DDR SDRAM; the Intel i875 chipset will only work with systems using Pentium 4 processors or Celeron processors that have a clock speed greater than 1.3 GHz and utilize DDR SDRAM, and the Intel i915g chipset only works with the Intel Pentium 4 and the Celeron, but it can use DDR or DDR2 memory.

Test

After start clock generator ic  give supply,reset,clock signal voltage to ICH,PCH,CPU and graphics controller.

1. Clock Generator Crystal - 14.31818 MHZ ok  Crystal is Working
2. Clock Generator Pin 5  -  14.31818 MhZ ok Clock Generator is Working.  Signal Goes to ICH
3. MIni Wann Card - Pin 22 PLT Reset   3.3 volt ICH OK. If No Voltage shoult check ICH
4. CPU - Reset voltage in Cpu Socket  PCH OK
5. CPU - Power Good voltage in CPU Socket CPU Power Good OK