PCI Express (Peripheral Component Interconnect Express) often goes by the name PCI-E and it is a standard form of connection that is established among the internal devices in any computer system.
On the usual terms, the PCI Express is generally used for representing the actual expansion slots that are present on the motherboard which accepts the PCIe-based expansion cards and to several types of expansion cards themselves.
The computer systems might contain several types of expansion slots, PCI Express is still considered to be the standard device for establishing the connection between various internal devices.
Different Formats Of PCI Express
You would come across various formats of the PCI Express including PCI Express x1, PCI Express 3.0, PCI Express x16 and so more.
However, several users are confused about the exact meaning of “x” in PCI Expressformats, how to tell which type of format would support the particular computer system, what options are available and so more.
It is usually not possible to determine the particular type of the various PCIe technologies that might work better with one computer. However, once the users have understood the important aspects and major differences among each format and PCI Express version, then it becomes all easy to realize the same.
So, Now Let’s Start With PCI Express Versions
During the early stages of development, the PCI Express was initially known as “High-Speed Interconnect” (HSI). From various changes in its name like 3GIO (3rdGeneration Input/Output) and PCI-SIG finally settled for the name PCI Express.
PCI Express is a form of technology that is always under some sort of technical modifications. Here are some of the basic versions of the PCI Express that have been used in the computer systems for their high performance and efficiency parameters:
- PCI Express 1: It was in 2005 that PCI-SIG had introduced the PCI Express 1version. This was an updated version of the previous PCI Express 1.0a (launched in 2003) that came with several improvements and clarifications.
- PCI Express 2: PCI-SIG had announced the availability of the PCI Express 2.0version in 2007 that came with doubled transfer rate in comparison to the PCI Express 1 version. Even the per-lane throughout was increased from 250 MBps to 500 MBps. The PCI Express 2.0 motherboard is entirely backward compatible with the presence of PCI Express v1.x The PCI-SIG also claimed of several improvements in the feature list of PCI Express 2.0 from point-to-point data transfer protocol along with the software architecture.
- PCI Express 3: It was in 2007 that PCI-SIG had announced that the version of PCI Express 3.0 would be offering a bit rate of 8 Giga-transfers per second (GT/s).Moreover, it was also supposed to be backward compatible with the current implementations of the existing PCI Express PCI Express 3.0 came with an upgraded encoding scheme to around 128b/130b from the previous encoding scheme of 8b/10b.
PCI Express Versions: 1.0 VS 2.0 VS 3.0
Any particular number of the PCI Express that you would spot on the computer system or the motherboard, it would indicate the latest version along with its specific number of the PCI Express version that is supported by the computer system.
Here Is A Small Comparison Of The PCI Express Versions:
- PCI Express 1.0: 2 Gbit/s per lane (32 Gbit/s in an x16 slot)
- PCI Express 2.0: 4 Gbit/s per lane (64 Gbit/s in an x16 slot)
- PCI Express 3.0: 8 Gbit/s per lane (128 Gbit/s in an x16 slot)
In addition to this, each latest version of the PCI Express comes with additional improved specifications and functional performance.
For instance, PCI Express 2.0 version comes with doubled transfer rate than of the previous PCI Express 1.0 version. It also comes with improved per-lane throughput from 250 Mbps to 500 Mbps.
Similarly, PCI Express 3.0 comes with an upgraded encoding scheme of 128b/130b from the previous 8b/10b encoding scheme. It, therefore, reduces the bandwidth overhead from around 20 percent of the previous PCI Express 2.0 version to a mere of around 1.38 percent in PCI Express 3.0. This major improvement has been achieved by a technical process referred to as “scrambling”.
The process of scrambling makes use of a recognized binary polynomial to a particular data stream in the feedback topology. As the scrambling polynomial is recognized, therefore, the data is able to be recovered by running the same through a particular feedback topology which makes use of the inverse polynomial.
In addition to this, the 8 GT/s bit rate of the PCI Express 3.0 version also delivers 985 MBps per lane effectively. This tends to practically double the overall lane bandwidth in comparison to the older versions of PCI Express 2.0 and PCI Express 1.0.
All of the PCI Express versions are both forward as well as backward compatible. This implies that irrespective of the particular version of the PCI Express your computer system or motherboard is able to support, they should be working together, at least at some minimum level.
As one can observe that the major updates to different versions of the PCI Express have increased the overall bandwidth drastically each time. Therefore, this feature greatly increases the potential of what the particular connected hardware is able to do.
As a result, the overall performance of the computer system in coordination with the different hardware components gets enhanced.
In addition to the overall performance enhancements, the update to different versions of the PCI Express also tend to bring about effective bug fixes, additional technical features, and improved power management.
On top of it all, the improvement in the bandwidth is the most significant change that is brought about by any update of the PCI Express version.