The Platform Controller Hub is the chipset on Intel platforms. It connects the processor to most of the board's peripherals and plays a central role in power-on. On older and larger laptops it is a separate BGA chip near the CPU; on many recent low-power designs it is inside the processor package, though it remains a distinct block in schematics and datasheets. AMD's equivalent is the fusion controller hub (FCH), integrated into the processor package on laptop parts.

What the PCH handles

  • USB ports, often through redrivers or port controllers on the board;
  • storage — SATA ports and some PCIe lanes for SSDs;
  • audio — the HD Audio bus to the codec;
  • the BIOS flash — reading the SPI chip at power-on;
  • the EC link — eSPI or LPC to the embedded controller;
  • power management — the sleep-state signals (SLP_S3#, SLP_S4#, SLP_S5#), resume reset input and the platform reset output;
  • the Intel Management Engine, which runs on a controller inside it.

Its role in the power-on sequence

The PCH sits at the centre of the sequence:

  1. Standby power arrives and the EC releases the PCH from resume reset (RSMRST#).
  2. A power button event reaches the PCH's power button input.
  3. The PCH releases its sleep signals, telling the board to switch on memory and system rails.
  4. When the power-good signals arrive, the PCH releases the platform reset (PLTRST#) and the processor starts.

When a board stops at one of these steps, the PCH's inputs and outputs are among the first things to check — see Power Sequence Pages in Laptop Schematics Explained.

How PCH faults show up

  • the board accepts standby power but never responds to the power button, even with a healthy EC and resume reset;
  • all USB ports or all storage fail at once;
  • the PCH runs hot in standby, often after liquid damage or a surge;
  • intermittent faults when the board flexes, pointing at cracked BGA joints.

These symptoms also have simpler causes, so check rails and signals around the chip before condemning it. Signs that do point at the chip itself are discussed in Signs of PCH (Chipset) Failure in Laptops.