Graphics cards

PCIe or AGP?

Graphics cards will come in one of two varieties: AGP or PCI Express (PCIe). AGP and PCIe are types of expansion slots on your PC's motherboard where you plug in the graphics card. Although there a few exceptions, your motherboard will only support one of the two types, so you need to be sure which it is before you go and buy a graphics card.

AGP is the older standard, and it comes in various flavours up to 8x (this is the most common one in motherboards less than two years old). In an AGP motherboard, there will be only one AGP slot. An AGP motherboard will also have PCI slots, but don't confuse those with PCIe slots. You can't put a PCIe graphics card in a PCI slot.

ABit AN8 PCI-e motherboard

PCIe has recently supplanted AGP, and most new motherboards and systems use it. PCIe slots also come in different flavours: 1x, 4x, 8x, 16x and 32x. A motherboard with PCIe will have a mix of the types. For instance, a motherboard might have one 16x PCIe slot and four 1x PCIe slots. Most current PCIe graphics cards require 16x slots.

PCIe is considerably better than AGP, although that fact may not be realised in the current generation of graphics cards. A card in a 16x PCIe slot can communicate with the PC's CPU and memory at twice the speed of one in an 8x AGP slot.

In addition to speed, PCIe has another advantage - the ability to put more than one graphics card in the PC. A motherboard can only have one AGP slot, but more than one 16x PCIe slot is possible (though not common). Some Nvidia graphics cards are designed to work together to render a scene, effectively splitting the load if you have more than one card in the PC. This configuration is called the scalable link interface (SLI).

Motherboards with two PCIe slots (such as those based on the Nvidia nForce4 SLI chipset) will also allow you to install two different graphics cards in a non-SLI configuration (that is, the cards are not connected to each other to boost rendering performance) so that you can use up to four monitors on one PC!

This type of functionality is suitable for those of you who work with large image or audio editing applications and require as much screen real estate space as possible. Conveniently, to implement this type of multi-monitor support, you don not have to use identical cards or even cards of the same make. A card based on an Nvidia chipset will work in conjunction with an ATI chipset-based card. You will need to use an operating system that supports multiple monitors in order to be able to enable this feature though. Windows XP Pro or Home does the job very well.

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