What are the differences between PCI / AGP / PCI-E graphics card interfaces?

PCI-E interface As the motherboard may be the largest interface, it has a wide range of applications. What is the difference between it and other PCI and AGP?

PCI-E interface is a common interface standard for the motherboard. At present, it mainly provides devices that directly communicate with the CPU. It is usually to expand the functions not supported by the motherboard, such as independent graphics cards, so as to output stronger graphics capability for the platform and make up for the deficiency of core display.

PCI-E interface Independent graphics card.

Recently, SSD products with PCI-E interface and m.2 interface, SSD products supporting nvme protocol communicate with the processor through PCI-E bus, and the maximum bandwidth of pci-e3.0x4 is supported. The author will explain this bandwidth later.

PCI interface.

The full English name of PCI bus is pcisig, which is a local parallel bus standard published by pcisig (PCI special interest group). PCI bus standard was formulated in 1992, older than the wolf. Its emergence was developed by ISA (industry stand ard Architecture) bus.

The data width of the ordinary PCI interface is 32 bits (bit, which is often referred to as b), the interaction speed is 33MHz, and the theoretical maximum bandwidth is 4byte / s * 33MHz = 133mb / s. here it becomes byte bytes, which is commonly referred to as large B. because the data on the computer is binary, the 33MHz of this equation should actually be 33.333. Hyperbolic cosine of. Hyperbolic cosine of.

The PCI-X with higher transmission speed sold later is still the PCI bus standard adopted. By increasing the number of pins to improve the speed, the new pci64 / 66 specification provides 64 bit data width and 66MHz working frequency, and the theoretical bandwidth is increased to 533mb / s. This idea seems to merge two PCI interfaces, but it is not exactly the same.

AGP interface.

AGP is a new standard developed on the basis of PCI bus, which is specially proposed for higher and higher image processing requirements. However, its main purpose is to solve the communication problem between display card and processor, so it is only a port. This means that only one terminal can be connected, and this terminal must be a graphics accelerator card. PCI is a bus that can connect a variety of terminals, graphics cards, network cards, SCSI cards, sound cards, etc.

AGP follows the PCI standard with 32-bit data width, but the operating frequency starts from 66MHz. Agp1x standard can provide a theoretical bandwidth of 266mb / s. In the version of agp2x, a new bidirectional data transmission technology (data transmission on rising and falling edges) is adopted, and the theoretical bandwidth is doubled to 533mb / s.

After the geometry of picture processing requirements increases, the bandwidth of agp2x is insufficient, agp4x is born, and the working frequency remains unchanged. By increasing the data width, the theoretical bandwidth is doubled to 1066mb / s. In the later agp8x version, the bandwidth is doubled again to 2133mb / s.

Later, when the high occupancy defect of AGP was emphasized and the increase of bandwidth became difficult, the PCI Express, that is, the PCI-E standard, was confirmed in 2002. However, due to the high initial price, the motherboard was equipped with AGP and PCI-E interfaces at the same time. For a long time, users advocated to choose AGP graphics card installation machine.

PCI-E interface.

Finally, PCI-E interface has become the top priority. It is also the most widely used general interface at present. The bandwidth is divided into 1x / 2x / 4x / 8x / 16x. At present, other interfaces on the motherboard are rare, mainly PCI-E expansion interfaces, and 2x slots are also rare.

PCI-E interface changes the parallel data transmission mode used by PCI and AGP to serial transmission mode. The advantage of serial transmission is faster transmission speed, but the disadvantage is prone to data loss, but this disadvantage is not a problem in front of the continuous progress of new technologies.

PCI-E interface motherboard.

Pci-e1.0 standard provides 2.5gt/s (gigatransmission permission, i.e. transmission times per second, which is different from Gbps) transmission speed. Commonly used pci-ex16 provides 16 bit data width, and its unidirectional theoretical bandwidth has reached 5GB / s. due to series transmission, pci-e2.0 previously adopted 8bit / 10bit standard, and the start flag and end flag will be added when transmitting data, The actual transmission of 8bit data needs to occupy 10bit transmission capacity, so the actual unidirectional transmission speed is about 4GB / s. Even so, it is far more than 2.1gb/s of agp8x. It includes two-way data transmission (data transmission on rising and falling edges), and its actual bandwidth can reach 8GB / s.

Although the pci-e2.0 standard has no major correction, it doubles the transmission speed of 2.5gt/s to 5.0gt/s. Without any change, the bidirectional bandwidth of pci-e2.0x16 is 16GB / s.

At present, the most widely used pci-e3.0 standard not only improves the transmission speed to 8gt / s, but also upgrades the transmission standard to 128bit / 130bit, the code loss can be almost ignored, and the theoretical bidirectional bandwidth of pci-e3.0x16 can reach 32GB / s.

The pci-e3.0x4 interface adopted by the nvme protocol SSD recently supports a maximum bandwidth of 8GB / s, but the hard disk cannot read and write at the same time. Its maximum bandwidth is unidirectional 4GB / s, i.e. 32GB / s, and the unit is converted to 1byte (byte) = 8bit (unit).

Shenglan Technology Co., Ltd_ It focuses on the production of electronic connectors and research and development of precision components. Its products are widely used in consumer electronics, new energy vehicles, USB, 5g and other fields. Its industrial lines cover the Pearl River Delta, Southeast Asia and other regions. It has established long-term strategic cooperation relations with well-known enterprises such as Foxconn, Lixun precision, Huawei, Xiaomi, TCL, Hitachi Group, BYD and Great Wall Motors, with IATF 16949, ISO9001 ISO14001, QC080000 and other system certification and product safety certification, and provide professional connection and manufacturing solutions for the industry http://jctc.com.cn/