14Aug Microprocessors

There are typically five serviceable components on the system board. These include:

The Microprocessor
The Ram modules
The CMOS backup battery
The ROM bios IC(s)
The cache memory

Of the five items listed, three- the microprocessor, the RAM modules and the cache memory-can be exchanged to increase the performance of the system. These devices are normally mounted in sockets to make replacing and upgrading them an easy task.

PC manufacturers mount microprocessors in sockets so that they can be replaced easily. This enables a failed microprocessor to simply be exchanged with a working unit.

The notches and dots of various ICs are important keys when replacing a microprocessor. They specify the location of the Ic’s number 1 pin. This pin must be lined up with the pin 1 notch of the socket for proper insertion. An arm activated clamping mechanism in the socket shifts to the side, locking the pins in place. To release the microprocessor from the socket the lever arm beside the socket must be pressed down and away from the socket.When it comes free from the socket, the arm raises up to release the pressure from the microprocessor’s pins.

The dot and the notch should be located at the free end of the socket’s locking lever for proper installation. Both the CPU and the socket have one corner that doesnot have a pin in it. This feature prevents the CPU from being inserted into the socket incorrectly.

Pentium processors generate a considerable amount of heat during normal operation. To prevent this heat from reaching a destructive level for the device, a pentiums require that a CPU cooling fan and heat sink unit be installed on the microprocessor. These units are available on glue on and snap on models. A special heat conducting grease is typically used with snap on heat sinks to provide good thermal transfer between the microprocessor and the sink. Power for the fans is normally obtained from one of the system’s option power connectors, or from a special jumper block on the system board. These items must be installed before operating the microprocessors.