Rosewill Computer Case 422 Información técnica descargar pdf (Pagina 58)

Purposes of a Power Supply

141

Disassembly

and Power

Tech

Tip

Tech

Tip

Power converters and Y connectors are good to have in your tool kit

In case a service call involves adding a new device, having various power converters

available as part of your tool kit is smart.

Figure 4.23 Y Molex connector

Purposes of a Power Supply

The power from a wall outlet is high-voltage AC. The type of power computers need is low-

voltage DC. All computer parts (the electronic chips on the motherboard and adapters, the

electronics on the drives, and the motors in the hard drive and optical drive) need DC power

to operate. Power supplies in general come in two types: linear and switching. Computers use

switching power supplies. The main functions of a power supply include the following:

• Convert AC to DC

• Provide DC voltage to the motherboard, adapters, and peripheral devices

• Provide cooling and facilitate air flow through the case

One purpose of a power supply is to convert AC to DC so the computer has proper power

to run its components. An ATX power supply does not connect to the front panel switch as the

old AT-style power supplies did. With the ATX power supply, a connection from the front panel

switch to the motherboard simply provides a 5-volt signal that allows the motherboard to tell

the power supply to turn on. This 5-volt signal allows ATX power supplies to support ACPI,

which is covered later in the chapter, and also lets the motherboard and operating system con-

trol the power supply. Figures 4.24 and 4.25 show the front panel connections to the mother-

board on two different computers.

On an ATX power supply that has an on/off switch, ensure that it is set to

the on position

If an ATX power supply switch is present and in the off position, the motherboard and

operating system cannot turn on the power supply. Some ATX power supplies do not have

external on/off switches, and the computer can be powered down only via the operating

system.

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Rosewill Computer Case 422 Información técnica Pagina 58