PCIe and USB transmission speed Summary

The speed of each PCIe standard is as follows:

 

Version	Release Date	Original data transmission bandwidth	Valid bandwidth	Single lane bandwidth	Total Bandwidth (x16)
Pcie1.x	2003	2.5gt/s	2 Gbps	250 MB/S	8 Gb/s
Pcie2.x	2007	5.0gt/s	4 Gbps	500 MB/S	16 Gb/s
Pcie3.0	2010	8.0gt/s	8 Gbps	1 Gb/s	32 Gb/s

 

After comparison, we found a strange problem. According to common sense, the bandwidth of the New Generation doubles the bandwidth of the previous generation. The original data transmission bandwidth of pcie3.0 should be 10gt/s, but only 8.0gt/s. We know that the 1.0 and 2.0 standards adopt the 8B/10B encoding method. That is to say, each 8-bit valid data is transmitted with a two-bit verification bit, actually, 10 bits of data need to be transmitted. Therefore, valid bandwidth = raw data transmission bandwidth * 80%.

In the 3.0 standard, a more effective 20% B/130B encoding scheme is used to avoid 3.0 bandwidth loss. 1.538% of the wasted bandwidth is only, which is negligible, therefore, the 8gt/S signal is no longer just a theoretical value, but a real transfer value.

The speed of each USB standard is as follows:

 

Version	Release Date	Data bandwidth	Data bandwidth
USB 1.0	1996	1.5 Mbps	192kb/s
USB 1.1	1998	18 Mbps	1.5 MB/S
USB 2.0	2000	480 Mbps	60 MB/S
USB 3.0	2008	5 Gbps	640 MB/S

 

It is worth noting that usb3.0 also uses the 8B/10B encoding method, so the actual transmission bandwidth should also be reduced to 640 Mb/s: 80% Mb/s * 512 = MB/S