Expansion slots

Expansion slots are specific slots on a PC motherboard that facilitate the placement of expansion cards.

All such expansion slots are colour coded, and are built in such a way that only a specific type of card or device can interface with/ be inserted into the device.

Types

Common types of expansion slots are PCI, PCI-X, PCI Express and AGP.

PCI

Main article: Conventional PCI

Peripheral Controller Interface these operate at either 33 or 66 MHz and 64 bits. This utilises parallel technology.

PCI-X

Main article: PCI-X

This is the latest version of PCI technology operating at 66 MHZ and 64 bits. This also utilises parallel technology.

PCI Express

Main article: PCI Express

This had less channels for data but it was much faster than AGP technology. It was cheaper to design and build. This type of slot was much more upgradeable/expandable. It was also serial technology.

AGP

Main article: Accelerated Graphics Port

This was a designated slot reserved for graphics cards. It was utilised in a motherboard that would be used in a PC that required high-end graphics processing abilities.

AGP Pro

Used for Mac's that require high re-draw capabilities. A good example would be a PC running AutoCAD. Some slots required up to 110W of dedicated power, this would be delivered using a power supply with its own MOLEX.

Slot power supply

PCI slots

Can supply a maximum of 5V. It is important to note that a 5V card would not fit into a 3.3V slots. There are cards that can operate on two voltages they automatically default to the lower voltage.

AGP slots

These work on either 3.3V or 1.5V.

See also

• Expansion card
• Motherboard

Notes

In recent times however we have seen the gradual replacement of AGP slots and cards with PCI type slots and cards. They have proven to be faster. They have also proven themselves to be more versatile as a greater number of components can be attached to a PCI slot via the right PCI card. This can also lend itself to extending the capabilities of the PC.