What is PCI Express? Do you need PCIe 4.0 in your computer?

Let's understand the differences between the PCI-E connector.

Typically, this high-speed port refers to the actual expansion slots on the motherboard that accept traditional PCIe-based expansion cards and expansion card types.

Old video card with AGP interface

PCI Express has virtually replaced AGP and PCI, both of which have replaced the oldest widely used connection type called ISA. Although PCs can contain a variety of expansion slots, PCI Express is considered the standard internal interface for the fastest slot. Today, many personal computer motherboards are manufactured only with PCI Express connectors.

How does PCI Express work?

Like older standards like PCI and AGP, the Express-based device physically goes into a high-speed connector on the motherboard.

The interface of this connector provides high-speed communication between the device and the system board, as well as other equipment.

Although not very common, there is also an external version of the high-speed port, unsurprisingly called External PCI Express, but often shortened to PCIe. ePCIe devices that are external require a special cable to connect any external PCIe device to the PC through a PCIe port, usually located on the back of the PC, supplied either by the motherboard or a dedicated internal PCIe card.

What types of PCI Express cards are there?

With the demand for faster, more realistic video games and video editing tools, graphics cards were the first types of computer peripherals to take advantage of the benefits offered directly by PCIe.

While graphics cards are still the most common type of PCIe card, you'll find other devices that connect to the motherboard, processor, and RAM much faster. It is also increasingly common to make PCIe connections instead of conventional PCI. For example, many high-end sound cards now use a high-speed port, as well as an increasing number of wired and wireless network interface cards.

Hard drive controller cards may be the most useful for PCI-E after the video card. Connecting a high-speed PCIe SSD to this high-speed interface allows you to read and then write the disk much faster. Some PCIe hard drive controllers even include an integrated SSD, greatly changing how storage devices are traditionally connected inside a PC.

Of course, with PCIe being replaced by PCI and AGP entirely on newer motherboards, almost every type of internal expansion card based on older interfaces is being rebuilt to be able to use the PCI Express bus. This includes things like USB expansion cards, Bluetooth cards, etc.

More information about processor and chipset lines

Let's move from theory closer to practice. We have already found out that the actual “owners” of the PCIe lines are the processor and the chipset, although no one prohibits other devices from exchanging data with each other over these lines. To understand in more detail, let's look at each socket separately.

AMD AM4

Let's take, for example, the AMD Ryzen 7 5800X CPU and the X570 chipset for it.

The illustration shows a conventional 5000 series processor indicating the interface lines. It shows that the processor has 16 lines for the video card and 4 for the SSD. Total 20. Sometimes you can find mention that there are 24 lines, but this takes into account the four that connect the CPU to the chipset. These lines cannot be reconfigured in any way and their mention is only valid for statistics.

Those lines that go to the video card, or rather to the connector for it, can be divided between two connectors to support SLI/Crossfire technologies. In this case, the lines are distributed equally between two connectors (x8/x8 mode) or the second one operates in x4 mode.

Four processor lines for drives are output to the M.2 connector closest to the CPU socket.

The number of available lines for a chipset depends on its model. Thus, the X570 has 16 lanes, 8 of which can be freely configured by motherboard manufacturers, and another 8 can be used for SATA or drives/connectors. At the same time, the 4th generation interface will be used.

The B550 and A520 chipsets can only use PCIe 3.0, even for CPU communication. The lines themselves are also smaller, 10 and 6, respectively.

Intel 1200

At the moment, this is the “freshest” socket for 10th and 11th generation processors. Let's take a closer look at the latest Rocket Lake CPU. The line configuration here is the same as that of competitors - 16 lines for the video card and 4 for the drive. True, communication with the chipset is still carried out via the DMI3 bus, which is actually PCIe 3.0, but there are now 8 such lines, not 4.

The older Z590 chipset has 24 PCIe 3.0 lanes, which makes it possible to install several M.2, as well as several PCIe 3.0 x4 and/or PCIe x1 slots. The Z570 has 20 lines, the B560 has 12, and the younger A510 is content with 6.

What are the different PCI Express formats?

Shown are the various controllers on the Express x1...Express 3.0...Express x16 motherboard
. What does "x" mean? How do you know if your PC supports it? If there is a PCI Express x1 card, and there is only an Express x16 slot, does it work compatible? If not, what are your options?

It's often not entirely clear when you buy an expansion card for your computer, such as a new graphics card, which of the various PCIe technologies works better with your PC than the other. However, as complex as it is, it looks quite simple once you understand two important pieces of information about a high-speed port: the part describing the physical size and the part describing the technology version, as described below.

PCIe sizes: x16, x8, x4, and x1

As the title suggests, the number after the x indicates the physical size of the PCI-E card or slot, with x16 being the largest and x1 the smallest.

Here's how the different sizes are formed:

Regardless of the size of the high-speed port or card, the key notch, that small space in the card or slot, is always located at pin 11. That is, the length of pin 11 continues to increase as we move from PCIe x1 to PCIe x16. This allows you to flexibly use cards of one size with slots of another.

PCIe cards fit in any high-performance port slot on the motherboard that is at least as large. For example, a PCIe x1 card will fit into any PCIe x4, PCIe x8, or PCIe x16 slot. The PCIe x8 card will fit into any PCIe x8 or PCIe x16 slot. PCIe cards that are larger than a PCIe slot can fit into the smaller slot, but only if that PCI-E slot is open (i.e. does not have a plug at the end of the slot).

Radeon PCI-Express x16 graphics card

In general, a larger Express card or slot will support more performance, assuming the two cards or slots you're comparing support the same version of PCIe.

Parallel interface

Centronics cable connector pin assignments

PCIe version: 4.0, 3.0, 2.0 and 1.0

Any number after PCIe that you find on a device or motherboard indicates the latest version number of the PCI Express specification being used.

Here's how the different versions of the PCI Express controller compare:

All versions of the high-speed port are backwards and forwards compatible, meaning no matter what version your PCIe card or motherboard supports, they should work together at least at a minimum level. As you can see, major updates to the port standard dramatically increase throughput each time, greatly increasing the potential of what the associated hardware can do.

The version's improvements also include bug fixes, added features, and improved power management, but the increase in bandwidth is the most important change to note from version to version.

RJ-45 connector (for twisted pair connection)

(the cable is directed away from the viewer)

When connecting a computer to a hub, the “normal” layout is used. When cascading hubs or when connecting a computer to a computer (without a hub), the “uplink” layout is used at one end of the cable, and the “normal” layout at the other.

Maximizing compatibility with PCIe

As you read in the sizes and versions sections above, uses almost any configuration you can imagine. If it's physically fit, it probably works... that's great. However, it's important to know that to increase bandwidth (which usually equates to maximum performance), you need to select the highest PCIe version supported by your motherboard and select the largest size of a given port that will fit.

For example, a graphics card with a 3.0 x16 high-speed port will give you maximum performance, but only if the motherboard supports the 3.0 high-speed port and has a free x16 high-speed port. If the motherboard model uses PCIe 2.0 exclusively, the card will only run at the supported speed (for example, 64 Gbps in an x16 slot).

Most motherboards and personal computers released in 2013 or later likely support Express v3.0. If you are unsure, check your motherboard or PC manual. If you can't find any definitive information about the PCI version your motherboard can use, I recommend buying the largest and latest version of PCIe card, if it fits, of course.

Adapter 9 to 15 contacts

What will replace PCIe?

VR Virtual Reality Headsets
Video game developers are always looking for games that become increasingly more realistic, but they can only do this if they can transfer more data from their game programs to a VR headset or PC screen, and this requires faster interfaces . Because of this, PCI Express will not continue to dominate its laurels. PCI Express 3.0 is amazingly fast, but the world is striving for incredibly fast transfers.

PCI Express 5.0, due to be completed by 2022, will use 31,504 gigabits per second of bandwidth per lane (3,938 megabytes per second), twice as much as the high-speed slot version 4.0 offers. There are a number of other interface standards other than PCIe that the tech industry is looking at, but since they will require major hardware changes, PCIe looks set to remain the leader for some, a long time as the fastest ever.

rardCrage hi bross

Serial data transfer

Serial interface (RS-232) connector pin assignments