Graphics Card Slots – All You Need To Know

A graphics adapter/card is an expansion card, whose primary function is to output images onto a display. Adapters nowadays offer accelerated rendering of 3D and 2D graphics. They can be of two types, integrated graphics adapters and dedicated graphics adapters. Integrated graphics adapters are embedded onto the motherboard, and share the system RAM, thus reducing overall performance. They are recommended for users who do not require to run advanced 3D applications. Dedicated graphics cards, on the other hand, are connected to the motherboard via expansion slots, have a dedicated processor and their own RAM, which allow for advanced rendering capabilities and thus reduce the workload of the CPU. Most motherboards with integrated graphics cards come with an expansion slot for a dedicated graphics card and the option to disable the integrated graphics card. Confused about the various graphics card slots and their differences? We explain it all.

Graphics Card Slots – Differences and more:

There are essentially two ways to connect a graphic card to a motherboard. One way is via an AGP slot, or a PCI Express (PCIe) slot. Your motherboard will only support one of these slots. Usually, motherboards manufactured in 2004 or earlier come with the AGP slot, motherboards manufactured in or after 2004 come with the PCIe slot.

AGP stands for “Accelerated Graphics Port”, it was introduced in 1997. It was the first bus dedicated only to graphics adapters. Created by Intel, it allowed for higher data transfer rates, since the previous graphics adapters used to utilize the all-purpose PCI expansion slot. With the advent of AGP, the graphics adapters had a direct pathway between the slot and the processor, without sharing the PCI bus like previously. AGP supports up to 2.133GB/s of data transfer. Microsoft first introduced AGP support into Windows 95 OEM Service Release 2, and the first Windows NT-based OS to receive AGP support was Windows NT 4.0 Service Pack 3 in 1997. Linux gained AGP support in 1999 with a kernel module called AGPgart. The latest graphics cards that used the AGP slot were cards from the ATi Radeon HD 4000 series and a few cards from the Nvidia GeForce 7 series.

PCIe stands for “Peripheral Component Interconnect Express”; it was introduced in 2004 as a joint venture between Intel, IBM, Dell and Hewlett-Packard. PCIe slots allowed for even higher data transfer rates than its predecessors, supporting up to 16GB/s of data transfer. PCIe, unlike AGP, is not only for graphics adapters, but for LAN/WLAN cards as well. The initial PCIe slot introduced in 2004, PCIe 1.0 supported up to 4GB/s of data transfer. Subsequent versions, introduced in 2007 and November 2010 support up to 8GB/s and 16GB/s of data transfer. PCIe 3.0 has only been theoretically envisioned, only its specifications have been decided and manufacturers will start producing motherboards and devices with this protocol sometime later this year. Motherboards and devices using PCIe 3.0 are expected to come into markets sometime in late Q3 2011 or early Q4 2011.

So if you’re buying a motherboard and/or a graphics card now, you’re probably buying one that uses PCIe 2.0. AGP devices have been mostly phased out and it will be very hard finding any graphics adapters that use AGP.

As a side note, let it be known that the capability of a graphics card is not decided by the amount of memory it offers. The common misconception is that a graphics card with higher memory is a more capable card. It is not true, the capability of a graphics card is determined by the chipset and it’s rendering capability. As an example, let us consider an Nvidia GeForce 8400GT with 1GB of memory and an Nvidia GeForce 9600GT with 512MB of memory. The Nvidia GeForce 9600GT will outperform the Nvidia GeForce 8400GT because it is a more advanced and capable chipset.

The performance of two graphics cards using the same chipset, only differing in video memory can only be gauged at higher resolutions. At higher resolutions, the card with the higher memory will produce higher frames per second, because it can store larger textures. The higher the resolution goes, the bigger the textures get. Up to a certain resolution, both cards would perform identically, but after a certain resolution, the card with the higher memory would produce higher frames per second, simply because it can store more rendered textures and display them. The amount of memory is used to store textures, overlays, GPU programs and not to render the graphics onto the screen.

In other words, if you are gaming at high resolutions go for more memory and needless to say, look for a newer chipset. Granted, memory is important, but do not gauge the capability of a graphics card only by the amount of video memory it offers. PCIe is the standard for graphics adapters now, and it probably will be for a few more years to come. Do let us know what you thought about our article on graphics card hierarchy.