The Computer Case:
The computer case or chassis , is usually constructed of metal, holds all the primary electronic components of the computer & most of the drives. The case provides access to other devices via ports & connectors, & protects surrounding devices such as TVs, mobile, speakers etc, from the computer's EMI .
The size & configuration of the case that should be considered as follows:
- The bigger the case, the more components it can hold. This provides greater expansion potential. Bigger cases also provides better air flow which is essential for cooling & large cases are easier to work with.
- The more compact the case or chassis, the less or low expansion potential it has; working on it is often much more difficult & usually air flow is more restricted or blocked.
- Smaller cases or chassis that come with a power supply usually have lower wattage which results in reduction of number of internal devices that can be installed.
- The more features in a case or chassis design, like the power wattage or the number of bays, the more higher the cost.
Power Supply:
A power supply provides an electrical power to the computer components. It draws power from local alternating current(AC) source such as a wall outlet & converts it to either 3.3 or 5 volts Direct Current(DC) for on board electronic components or devices & 12 volts DC for motors & hard disk drives. It delivers both positive & negative direct current to the computer. Power supplies must also 'condition' the power input i.e. it must smooth out any radical changes in the quality of the electrical supply as many homes & offices have power that fluctuates for more than the delicate computer components can tolerate. If the fan should fail or cause the computer to behave erratically, the power supply must be replaced when replacing a power supply, there are three things to consider physical size, wattage & connectors. There are devices that can be used to protect the computer from power supply problems. These includes surge suppressors & un-interruptible power supplies (UPS).
Surge Suppressors:
A surge suppressor can be used to filter out the effects of voltage spikes & surges that are present in commercial power sources & smooth out power variations. However, almost nothing will shield a computer from a very close lightning strike. Surge suppressors are available from local computer dealers & superstores. Most power stripes within surge protection have a red indicator lights. If the light goes out it means that the unit is no longer proceeding protection & needs to be replaced. If the indicator light starts flashing, it means the power strip is failing & should be replaced immediately. Surge suppressors smooth out power variations & protects the computer from power fluctuations up to a point, however, for a complete protection from power fluctuation & outage, an uninterruptible power supply (UPS) is recommended.
Uninterruptible Power Supply (UPS):
A uninterruptible power supply is an inline battery backup that is installed between a computer & the wall outlet. A UPS protects the computer from surges & acts as a battery when the power dips or fails. It also provides a warning when the power source is above or below acceptable levels. Many UPS models can interact with the computer and initiate a safe shutdown in the event of a complete power failure. UPS device will need its own line & circuit breaker. One of the principal power drains is a monitor. To keep a system online as long as possible during or at a time of power failure, turn off the monitor immediately after the failure commences or occurs. When considering a UPS , we must take into account the amount of protection that is need. The watt rating of the UPS must be sufficient to supply the computer & all its peripherals with power for enough time to safety shut down the system.
Motherboards :
The motherboard serves as the computer's back bone. All devices in a computer are connected to it in some way(direct or indirect way); it hosts the largest single collection of chips of any computer component & links all the components, making it possible for them to communicate. The motherboard also defines the computers limits of speed, memory & expand-ability.The motherboard is usually the largest circuit board that is usually found inside the computer case or chassis. Motherboards come in a number of sizes or form factors of which AT & ATX form factor are the two main varieties.
The CMOS Battery:
The CMOS chip requires a small or few amount of voltage from a battery to retain its memory. When the battery get low or dies, the computer will experience a sudden memory less & thus settings. The voltage of CMOS battery ranges from 3 to 6 volts. The CMOS chip contain a capacitor that allows us to replace the battery without losing any data.
Power On Self Test:
Every time a computer boot up or reset using the Reset button or the windows Restart command, the computer reboots & reset to its basic or the default operating conditions. The system BIOS program starts by invoking or executing a special program stored on ROM chip called Power-On-Self-Test (POST). The POST sends out or circulate the standardized commands that checks every primary devices in other words, it runs or executes an internal self diagnostic routine. The POST has two stages: one occurs before & during the text of the video of the other that occurs after the video has been tested . The division determines whether the computer will alert you to errors by beeping or showing them on the screen.
