▷ Pci vs pci express: characteristics and differences

Peripheral Component Interconnect (PCI) slots are such an integral part of PC architecture that most users take them for granted. For years, PCI has been a versatile and functional way to connect sound, video, and network cards to a motherboard. But the PCI has some shortcomings. As processors, video cards, sound cards, and networks have become faster and more powerful, PCI has remained the same. It has a fixed width of 32 bits and can handle only 5 devices at a time.

The new protocol called PCI Express (PCIe) eliminates many of these shortcomings, provides more bandwidth, and is compatible with existing operating systems. In this article, we'll take a look at what makes PCI Express different from PCI. We will also see how PCI Express makes a PC faster and can replace the AGP slot.

Index of contents

What are the differences between PCI slots and PCI Express slots?

In the early days of computing, a large amount of data moved through serial connections. Computers separated the data into packets and then moved the packets from one place to another at a time. Serial connections were reliable but slow, so manufacturers began using parallel connections to send multiple data simultaneously.

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It turns out that parallel connections have their own problems as speeds increase more and more, for example, cables can interfere with each other electromagnetically, so now the pendulum is rotating towards highly optimized series connections. Improvements in hardware and the process of splitting, tagging, and reassembling packets have led to much faster serial connections, such as USB 2.0 and FireWire.

PCI Express is a serial connection that works more like a network than a bus. Instead of a bus that handles data from multiple sources, PCIe has a switch that controls multiple point-to-point serial connections. These connections extend from the switch, leading directly to the devices where the data should go. Each device has its own dedicated connection, so devices no longer share bandwidth as they do on a normal bus.

When the PC starts, PCIe determines which devices are connected to the motherboard. Then identify the links between the devices, creating a map of where the traffic will go and negotiating the width of each link. This device and connection identification is the same protocol that PCI uses, so PCIe requires no changes to software or operating systems. Each lane or lane of a PCI Express connection contains two pairs of cables: one to send and one to receive. Data packets move through the lane at a rate of one bit per cycle. An x1 connection, the smallest PCIe connection, has a four-wire rail. It takes one bit per cycle in each direction. A link x2 contains eight cables and transmits two bits at a time, a link x4 transmits four bits, and so on. Other settings are x12, x16, and x32.

PCI

PCI Express

PCI Express is the interface with the most potential for the future and has made PCI ports obsolete

PCI Express is available for desktop and laptop computers. Its use can lead to a lower production cost of the motherboard, since its connections contain fewer pins than PCI connections. It also has the potential to support many devices, including Ethernet, USB 2, and video cards . The 32-bit PCI bus has a maximum speed of 33 MHz, allowing a maximum of 133 MB of data to pass through the bus per second.

However, a single PCI Express lane can handle 200 MB of traffic in each direction per second. A PCIe x16 connector can move an incredible 6.4 GB of data per second in each direction. At these speeds, an x1 connection can easily handle a Gigabit Ethernet connection, as well as audio and storage applications. An x16 connection can easily handle powerful graphics adapters.

A few simple advances have contributed to this massive jump in serial connection speed:

• Data prioritization, allowing the system to transfer the most important data first and helping to avoid bottlenecks. Time-dependent data transfers (in real time) Improvements in the physical materials used to make the connections. Better handshaking and error detection. Better methods to break data into bundles and put them back together. Also, since each device has its own dedicated point-to-point connection to the switch, signals from multiple sources no longer have to make their way through the same bus.

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Higher performance

We have established that PCIe can eliminate the need for an AGP connection. A PCIe x16 slot can hold much more data per second than AGP 8x connections allow. Additionally, a PCIe x16 slot can supply 75 watts of power to the graphics card, unlike the 42-watt AGP 8x connection. But PCIe has even more impressive potential for the future of graphics technology.

With the right hardware, a motherboard with two PCIe x16 connections can support two graphics cards at the same time. Nvidia and AMD have developed and released systems to take advantage of this feature. The cards work together by dividing the screen in half. Each card controls half of the screen and the connector makes sure everything is in sync. AMD's technology does not require identical video cards, a major difference from Nvidia, although high-performance systems must have identical cards.

Since PCI and PCI Express are compatible, the two can coexist indefinitely. So far, graphics cards have made the fastest transition to the PCIe format. Network and sound adapters, as well as other peripherals, have been slower to develop. But since PCIe is compatible with current operating systems and can provide faster speeds, they have ended up replacing PCI as a PC standard. Gradually, PCI-based cards became obsolete.

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Wikipedia source