| CPU - Central Processing Unit |
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| Your computer's CPU (or
processor) is centrally located on its motherboard, and it is the brain of your PC. The CPU
carries out much of the work on your system, and is constantly passing data and receiving
instructions. There are many brand names and many manufacturers of CPUs, and the
manufacturers are often producing several models at once, which overlap. This can make for a
difficult time in identifying your computer's particular CPU. Special Utility Diagnostics
programs can tell you the family, model, and mask of your CPU. |
CPU
(Click to Enlarge) |
CPUs are usually specified by two main parameters:
- Speed: cycles per second counted in megahertz (MHz).
- Width: I/O bus, internal registers and memory address bus.
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| For example, a Pentium II 333MHz has a 64-bit I/O bus width, a
32-bit internal register size, and a 36-bit memory address bus width. An older 486 DX4 had a
CPU speed of 100 MHz, and 32-bit I/O bus, internal register and memory address bus widths. |
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| These specifications, along with the manufacturer and model are what
uniquely identifies a given CPU. |
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| All of today's CPUs share a common need for cooling. The cooling
mechanisms (usually a fan and a heat sink) are matched to the CPU size, and must be
attached properly to provide maximum cooling. Most modern systems have an improved
motherboard design that provides for superior cooling of the CPU because of its position near the
power supply. |
CPU Fan
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| Modern systems have a Socket or Slot Number that facilitates
interchangeability of CPUs. These numbers (Socket 1, Socket 2, Socket 3 and so forth) are
directly related to the processor chips that they can support. Pentium II processors and
beyond use a slot where the processor card or cartridge is installed (Slot 1 or Slot 2). |
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| Upgrading Your CPU
One very common way of improving your system is to upgrade its CPU, thereby increasing clock
frequency, cache and other attributes that have a direct impact on your computer's performance. |
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| CPU upgrades are a relatively easy and common system improvement.
Upgrading the processor is often the fastest and easiest way to gain performance without upgrading
the entire motherboard. To maximize your motherboard you can almost always upgrade to the
fastest CPU that its processor socket will support. Some upgrades will require a voltage
regulator adapter. For example, if your motherboard has a Pentium Socket 5 with a 100MHz
CPU, you can upgrade to a Pentium MMX 233MHz, as long as you add in a 2.8v adapter. |
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| You need to stay within the same class when upgrading your CPU.
You can replace a slow 486 with a faster one, even possibly from a different vendor, but you can
not replace it with a Pentium without replacing your entire motherboard or purchasing a special
version of the new processor designed specifically for this type of upgrade. |
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| Be very careful when you replace your new
CPU that you install it properly aligned. If you accidentally put it in
sideways it is likely you will ruin your new CPU and your motherboard -- an expensive mistake.
From that point on your motherboard may ruin any chip you install. |
CPU
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| Don't forget that you should buy a new fan
when you upgrade your CPU. Better yet, get a boxed CPU with an integrated fan. That
way you'll know you are getting the proper size of fan. Make sure your fan has a
ball-bearing motor; the cheaper sleeve bearing motors often freeze after a very short life.
If you've max-ed out on your CPU then your next step is a motherboard upgrade. |
CPU Fan
(Click to Enlarge) |
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| CPU Problems
When a CPU fails, it generally fails in a big way. A
System that has not been changed recently, but suddenly does not boot, or freezes during the boot
process, is a good candidate for a CPU problem. |
CPU
(Click to Enlarge) |
If your computer powers up briefly, and perhaps even your hard drive
spins up, but then your system dies suddenly and completely, you may have a problem with your
CPU:
- Make sure that the CPU is installed securely in its socket
or slot. Make sure all system cables and connectors are secure.
- Check first for hardware conflicts or a defective peripheral device by removing all such
peripherals and expansion boards and attempting to start the system. If it starts, one of
the expansion devices is interrupting your system's operation. Re-install each device, one
at a time, and check the system, to determine which device is bad.
- Replace your CPU with a known, good, CPU in the motherboard. If it works, it is
probable that your CPU is bad, if it does not, you may have to replace your motherboard.
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CPU Socket
(Click to Enlarge) |
If your system starts up without a problem but then crashes or
freezes a few minutes after operation your CPU may be over-heating:
- Make sure that the CPU is installed securely in its socket or slot. Make sure all
cables and connectors are secure.
- Make sure your CPU heat-sink/fan is working properly.
If you do not have a fan, consider adding one.
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CPU Fan
(Click to Enlarge) |
If your system starts up without a problem but crashes or freezes
when a certain application is run:
- Try a known, good CPU in the motherboard.
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If you receive a beep code that indicates possible CPU fault:
- Check that the motherboard's power connector is securely
inserted.
- Try a known, good CPU in the motherboard. If the new CPU fails to correct the problem,
you may have to replace the motherboard.
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Power Cable
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If your system runs fine but your BIOS reports the wrong type of
CPU:
- The motherboard BIOS is not written to support your particular CPU directly.
- You may need a BIOS upgrade, if available. Contact your system or motherboard
manufacturer.
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| Over clocking
Over clocking is when a CPU is run at a speed higher than it is rated for. The concept
was not invented by high-tech users trying to get the most from their hardware, but by
unscrupulous vendors who, to save money, would install a CPU rated for less than the actual
operating speed. |
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| If you suspect that your vendor may have done this, you can look at
your chip's markings. Usually the part number will end in a suffix of -xxx where xxx is the
number indicating the maximum speed. For example -333 indicates that the chip was rated for
333MHz operation. One word of caution -- some vendors actually remarked the CPUs, obscuring
the original part number. |
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| Among the devotees, over clocking has become more of a religion than
a science. You can set jumpers on your motherboard to force your CPU to run faster
than it is designed to run. It is easy to be dazzled by the concept because the CPU is one
of the most expensive components on the motherboard, and faster-rated chips cost more money.
In addition, it is widely speculated that the manufacturers rate their chips conservatively. |
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| Despite this, we do not recommend over clocking here as the
chip will run hotter than it would normally. Symptoms of overheating include random lockups,
glitches and headaches. If you do decide to try to over clock your CPU and experience such
problems, it would be wise to return it to the original speed. |
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