To provide power to large internal Devices such as hard drive or CD/DVD drives and sometimes case fans or other devices.
Just adding this.
Powers IDE drives.
To provide power to large internal drives like hard drives and CD/DVD drives
A+ Answer: "powers IDE Drives"
molex 4-pin
stop cheating!
Typically a 2, or 3 pin 'fan' connector, or a 4-pin 'molex' connector. The 2-pin (positive/negative) and 3-pin (positive/negative/RPM) are most common, but older or cheaper fans, especially those not used on the CPU heatsink, may use a 4-pin 'Molex' connector. Other connectors may be used, including proprietary connectors, in the case of some motherboards, CPUs, and cases. This is common in videocards, which may need 2/3 pin, 4-pin molex, 4-pin PCI-E, 6-pin PCI-E, or 8-pin PCI-E connectors, or a combination thereof!
Molex Connectors are used in Power Supplies for powering up the devices. There are different types of Molex Connectors on Power Supply for. eg. 20 or 24 Pin Power Connector\ 4 Pin IDE device \ Sata Device Connector.Mini Molex refers to connector powering Floppy Disk Drives or AGP Cards on Computer System.
There are two kinds in common use:Molex - an older standard, but still commonSATA - Serial ATA, a newer standardSee the related links for pictures.
provide more power for the CPU
A Molex power connector is a 4-pin power connector found in most computer power supplies. It is used to provide power to large internal drives like hard drives and CD/DVD drives. They are slowly being replaced by SATA power connectors, which are easier to install can cannot be inserted incorrectly. They should not be confused with a Berg connector which is much smaller and is used to power floppy drives. The molex connector is used for IDE drives
Keep in mind I'm not a computer repair guy or at least not officially. The four pin molex connector from a power supply unit that you use to plug into hard drives, and other drives has a 5 volt wire and a 12 volt wire. The two black ones are ground or negative. The red wire is 5 volts DC, the yellow is 12 volts DC.
the optical drive will connect to the power supply with a connector called molex connecter it is a 4 prong connector
4 pins
To provide PC devices either 12 V AC or 5 V AC, or even ( 12 - 5 = ) 7 V AC. I don't really know whether any PC device uses 7 V AC...
24 pin connector is required to supply power to the motherboard.