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CPU & Cooler Installation

Install a processor, apply thermal paste, and mount the heatsink/cooler correctly

A Reference Briefing

Socket Types: LGA vs PGA

LGA (Land Grid Array) Pins are on the motherboard socket; the CPU has flat contacts. Used by Intel. Drop the chip in with zero force. Never press or drag. Bending a socket pin is often irreparable.

PGA (Pin Grid Array) Pins are on the CPU itself; the socket has holes. Used by AMD (AM4). Lower gently and press straight down with the ZIF lever. Bent pins on the chip are possible but sometimes repairable.

This lab covers LGA procedure, which is the dominant A+ exam scenario. The orientation rule (pin-1 triangle) applies to both types.

Pin-1 Orientation (the graded crux)

Every CPU has a small gold triangle on one corner. The socket has a matching marker (triangle, notch, or arrow). These must align before seating.

  • Wrong orientation by 90°, 180°, or 270° will prevent the load plate from closing cleanly.
  • On LGA sockets, forcing a misoriented CPU into the closed load plate bends the socket pins.
  • The socket notches/keys are asymmetric, making one correct orientation visually obvious.

Thermal Paste Amount

Paste fills microscopic air gaps between the CPU heat spreader and the cooler base.

  • Correct Pea-sized dot (roughly 4–5 mm) in the center. The cooler pressure spreads it evenly.
  • Too much Paste spills over edges. Excess acts as a thermal insulator, not conductor, and can contaminate the socket.
  • Too little / none Poor contact → CPU overheats, throttles, and can trigger thermal shutdown.

Fan Header: CPU_FAN vs SYS_FAN

CPU_FAN The only correct header for the CPU cooler fan. The motherboard monitors RPM and ramps fan speed based on CPU temperature. A missing connection triggers thermal protection and POST warnings.

SYS_FAN / CHA_FAN General case/chassis fans. These headers do NOT control or report CPU thermal status. Plugging the CPU cooler here leaves the CPU unmonitored and potentially uncontrolled.

Most boards label the header directly on the PCB silk-screen. It is a 4-pin PWM connector.

B CPU Installation Procedure

1

Open the socket: lift the retention lever and load plate

In Progress

LGA sockets use a hinged metal load plate held by a retention lever. Push the lever down and outward to release, then lift it to vertical. Raise the load plate fully so the socket contacts are exposed. Do not touch the socket pins.

2

Orient the CPU: align the pin-1 triangle

Locked

The socket diagram below shows the pin-1 marker in the bottom-left corner. Select the orientation that places the CPU's gold triangle at the matching socket marker.

Pin 1 LGA Socket (top view)

The CPU gold triangle must match the socket's pin-1 marker (gold triangle, bottom-left above). Select the CPU orientation:

3

Apply thermal paste to the CPU heat spreader

Locked

Apply thermal compound to the center of the CPU's integrated heat spreader (IHS). The cooler pressure will spread it. Select the correct amount:

Too Little
Poor contact → overheating
Pea-Sized Dot (Center)
Correct: spreads under cooler pressure
Too Much
Spills over → insulates + contaminates socket
4

Mount the heatsink/cooler and secure evenly

Locked

Lower the cooler straight onto the CPU. Tighten the four mounting screws in a cross (diagonal) pattern. Do not tighten one corner fully first, as uneven pressure bows the cooler and leaves hot spots. Tighten gradually in a star/X pattern until all four are snug.

5

Plug the fan cable into the correct motherboard header

Locked

The CPU cooler fan must connect to the motherboard's CPU_FAN header so the board can monitor RPM and ramp speed based on processor temperature. Select where you will plug the fan connector: