VAC would be the abbreviation of Volt Altern Current which would be translated Volts of alternating current. The difference between VDC is that its sinusoidal oscillation achieving a more efficient energy transmission.

The alternating current is the energy that we receive in our homes, it is generated in the power plants by means of alternators.

The intensity of this type of current varies with time, and changes direction 50 times throughsecond (50hz). The generated voltage changes in the form of sine wave so it is not constant.

In the image:

1. Current by pulsations.
2. Direct current (DC).
3. Alternating current (AC).
4. Variable current.

There are several cabinet heights according to the needs of the installation, this height can be measured in rack units (U).

Each rack unit or U is the distance between each horizontal separation to place the different accessories inside the rack. This distance is 1.75 inches that is equal to 4.4445 cm high.

For example, if we say that a rack is 8U we will understand that it has 8 units to install device orAccessories of 4.44 cm in height.

Normally these accessories, like trays, guides, strips, etc. Occupy a unit of U (1U), but we can find that other devices or accessories occupy more units, for example can be a rack box to install a PC, a UPS, etc. It can be said that there is also a half unit of U (0.5U), in this case, two units could be installed in a rack unit.

As far as I knowEndo the units of rack that occupy the devices that we are going to install we will know the height that we need for our rack.

The size of the rack unit (U) is based on the standard specification for racks defined in EIA-310.

ATX corresponds to a standard that was created to improve Baby-At. The idea of ??this improvement was rejoining carasterísticas to improve the speed and what it cost to mount a plate. ATX measures are 30.5 cm x 24.4 cm. From here in the ATX format we can be found different formats - E-ATX has measure 30 cm by 33 cm - ATX-30 having a measurement 30.5 24.4 cm - Mini ATX has a measure x 28.4 cm

Commonly referred to as internal Molex connectors on a desktop computer. It is used for peripherals that require more amperage than that provided by the data cable such as:

• Hard drives (IDE, SCSI and SATA)
• Units diskettes (3.5 'and 5.25 ")
• Optical drives (CD, DVD and Blu-Ray)
• Video cards (PCI-e plates, PCI and AGP)
• Cooling systems (air and liquid)
• Modding circuits (LEDs, light pipes, etc.)
• Naturally, there are two types of Molex connectors, a male connector and a female connector. Plugs are used to branch outlets and split them into two but most of the time are integrated into the PCB peripherals.

The electrical conductors exiting the power supply toward Molex connectors have colorsdistinguish:

Serial ATA or SATA (acronym for Serial Advanced Technology Attachment) is a data transfer interface between the motherboard and some storage devices such as hard disk, regrabadores readers and CD/DVD/BR, SSDs or other high performance devices are still being developed. SATA I Frequency: 1500 MHz Bits: 1. Bits 8 Real Speed: 150 MB/s. SATA II. Frequency: 3000 MHz Bits: 1 bits 8 Real Speed: 300 MB/s. SATA III Frequency: 6000 MHz Bits: 1. Bits 8 Real Speed: 600 MB/s eSATA. SATA type connector for connection of external peripherals.