CPUs
There are two major manufacturers in today’s market – Intel and AMD.
How a CPU will vary from CPU to CPU
The motherboard system bus carries information into and out of the CPU
When the system bus enters the CPU it is commonly called the front side bus and usually uses a 64-bit data path. Inside the CPU you have controllers that manage the basic functions of the CPU and control communication between the between the motherboard and other components within the CPU. These other components include one or more ALUs and the internal cache. An ALU (arithmetic Logic Unit) is responsible for performing complex calculations. Having multiple ALUs inside a single processor is what gave the early Pentiums their multiprocessing capabilities. Communication between the controller and the ALUs uses a 32-bit wide internal data bus. The bus system that supports communication between the cache system, the ALUs and controller is referred to as the backside bus.
CPU Speed
The most important thing you need to know about a processor is the speed at which it processes information. Unfortunately, there are several ways of measuring speed and they are frequently misleading. First, you should understand that speeds differ inside the processor and outside the processor. Internally, the processor may work up to 3.2GHz, but the system bus may only run at 800 MHz. Consequently, when you buy a new computer the CPU may be rated at 3.2GHz, but the question you really need to ask is what is the system bus speed, because that speed is the limiting factor that controls the actual functioning speed of your computer.
Advances in Processing Speed
CPU manufacturers have come up with more ways of doing more work faster. We said earlier that using multiple ALUs allowed for multiprocessing. This is the ability to simultaneously perform multiple functions. This is a misnomer. True multiple processing requires multiple processors. In other words, your system must be designed to support more than one CPU on a single motherboard.
Another option that’s recently been developed is the use of dual core processors. That means incorporating multiple processors with multiple ALUs inside a single CPU. These ALUs process information independently, but share the same controller.
Cache Memory
Cache uses SRAM or Static Ram as opposed to DRAM which the rest of the system uses. SRAM is faster, but more expensive than DRAM and holds memory without being refreshed. There are three types of cache – L1, L2 and L3. L1 cache is housed in the processor chip itself. L2 cache is inside the processor housing and not on the processor chip. L3 cache is also inside the processor housing, but further away from the processor chip.
Sockets
There are many varieties of sockets of which a processor fits. The two most common sockets in todays world are the LGA775 which are used with Intel Pentium 4 and Celeron processors and the 754 socket which is used by AMDs which is used by Athlon 64, Sempron and Opteron processors.
ZIF (Zero Insertion Force)
A lever is used to gently lock the CPU into the socket without damaging it.
HEAT
When installing a CPU, you must consider the problem of heat. The optimal temperature for your system is 100 degrees F, or 40 degrees C.
There are three solutions to controlling heat: a thermal compound is a cream like substance that you squeeze from a tube around the upper edges of the processor. The heat sink is set into this “goo” forming a seal between CPU and heat sink. The heat sink sits on top of the CPU drawing heat away from the CPU and towards the fan. The fan draws heat away from the CPU and expels it out of the case.