Pci vs agp vs pci express, the three interfaces used for graphics cards

The graphics card is the component in every PC that is responsible for processing everything we see represented on the monitor. Without a graphics card, you simply can't see what's going on with your PC, and therefore you can't do anything with it. Many PCs have video cards built into the processor itself, and others have additional cards that are connected to a certain type of video slot on the motherboard. In this article, we review the main slots that have been used to connect graphics cards in the PC world. PCI vs AGP vs PCI Express.

Just because your PC uses a video card built into the processor doesn't mean you can't upgrade and add a separate card. Just make sure you get the correct card type that matches the type of slot you have available on your motherboard. Fortunately, currently all graphics cards and all motherboards are based on the PCI Express format, so there really is nothing to consider in this regard when purchasing a graphics card. When it comes to choosing the right graphics card, you need to determine what it will do with your PC. Will you be surfing the internet and writing letters? Play high-end 3D video games or edit photos and home movies? Long ago we wrote an article to help our readers choose their new graphics card.

There have been 3 options when it comes to slots for connecting graphics cards to the PC. AGP (Accelerated Graphics Port), PCI (Peripheral Component Interconnect) and PCI Express. Each one has a different level of performance and different characteristics.

PCI

PCI is the oldest of the three types of graphics cards. PCI is also used for devices like sound and network cards. This type of slot uses a shared bus topology to allow communication between the different devices on the bus, providing a bandwidth of up to 133 Mbps with a 64-bit version that supports up to 512 Mbps.

PCI graphics cards can still offer high performance on older systems when you get a card with a good amount of built-in memory, 128MB or more. PCI provides fast communication between the CPU and peripherals, but peripheral devices have to compete with each other for bandwidth. PCI is capable of handling 2D images and general business graphics quite competently, but can be challenged by intense 3D graphics. That's where AGP comes in.

AGP

The AGP port was designed for use with 3D graphics applications. AGP uses a dedicated point-to-point channel so that the graphics controller can directly access main memory, thereby providing a bandwidth of 266 Mbps at 1.07 Gbps. To use an AGP video card, the motherboard must support it and include an AGP slot for the card.

The AGP specification is based on the PCI 2.1 specification, but unlike PCI, AGP is designed solely for use with graphics cards. It is not designed to replace the PCI interface like the general I / O interface bus, its main purpose is to deliver high performance graphics, including 3D images.

AGP has the ability to quadruple the theoretical bandwidth of PCI buses. This increased performance is achieved by introducing a dedicated point-to-point channel that gives the graphics controller direct access to the main memory of the system. Also, the AGP channel is 32 bits wide and runs at 66MHz, which translates to a total bandwidth of 266MBps.

AGP also supports two fast modes, 2x and 4x, which have a throughput of 533MBps and 1.07GBps respectively. Features like texture and pipeline further enhance AGP's graphics processing capabilities. Its direct memory execution mode allows texture data to be stored in main memory. Channeling is a process that allows the graphics card to send multiple instructions together instead of sending one at a time.

AGP improves the overall performance of a PC in several ways:

1. Graphics operations are faster because they do not have to share the bus bandwidth with other peripherals. Peripheral devices are also faster because they don't have to share the PCI bus with bandwidth-intensive graphics operations. AGP operates concurrently and independently of most transactions on the PCI bus. Since the AGP bus is handling all graphics tasks, the PCI bus is free to cater for devices such as disk controllers, modems, and network cards. The quality of 3D graphics created with AGP is very high, and since they are extremely realistic, the quality of 2D and 3D programs has been improved.

This type of slot is no longer found in current motherboards, nor are there any graphics cards on the market that use it, your only option would be to go to the second-hand market if you want to buy one for a very old PC.

PCI Express

PCI Express expands and doubles the data transfer rates of the standard PCI interface. PCI Express is a two-way serial connection (point-to-point bus) that avoids performance problems that can arise from sharing bandwidth on a common bus. It provides higher transfer speeds than PCI or AGP. It is also used with other devices such as network cards to achieve higher performance than the PCI standard. It is the AGP replacement for graphics cards.

Similar to previous standards like PCI and AGP, a PCI Express based device is physically inserted into a PCI Express slot on the motherboard. The PCI Express interface enables high-bandwidth communication between the device and the motherboard, as well as other hardware. Although it is not very common, there is also an external version of PCI Express, not surprisingly, it is called external PCI Express, but it is often reduced to ePCIe.

Being external, ePCIe devices require a special cable to connect to any external device, the ePCIe device is being used in the computer through an ePCIe port, usually located on the back of the PC, supplied by the motherboard or a special internal PCIe card.

If you want to learn more about PCI Express, we recommend reading the following articles:

• PCI Express - What is it and what is it for? PCI Express x16, x8, x4 and x1 connectors: differences and performance PCI vs PCI Express: characteristics and differences

This ends our special article on PCI vs AGP vs PCI Express, the three interfaces used for graphics cards, we hope you liked going back a bit to the past.

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