PCI-SIG Announces PCI-e 6.0 and Expects to Complete Specification in 2021
The organization overseeing the PCI standard announces the development of the PCI-e 6.0 standard. The data rate doubles compared to PCI-e 5.0 to 64GT/s, which enables a full duplex speed of up to 256GB/s. PCI-SIG expects to finalize the specification in 2021.
According to the PCI-SIG, the PCI-e 6.0 standard is backwards compatible with previous generations, despite some major innovations. In order to make the higher speeds possible, the use of the Non-Return-to-Zero technique is being abandoned. Pci-e 6.0 uses Pulse-Amplitude Modulation 4, or PAM4, instead of NRZ.
According to AnandTech, who attended a presentation about the new pci-e version, PAM4 has so far only been used in ultra high-end networking standards, such as 200Gigabit Ethernet. The technique doubles the transmission bandwidth per Hz relative to NRZ, but would be expensive to implement. Also, the signal is vulnerable, which is why Forward Error Correction is added to pci-e 6.0.
The announcement of pci-e 6.0 comes shortly after the announcement of the final pci-e 5.0 standard at the end of May. Now that the standard has been completed, manufacturers can start making products. Earlier this year, a group of tech giants announced that they were working on a new interconnect based on PCI-e 5.0.
It will probably be years before PCI-e 5.0 and 6.0 come to consumer products. This year will see the first consumer PCI-e 4.0 products in the form of video cards and SSDs. The final specifications of the PCI-e 4.0 standard were set at the end of 2017.
| 1.0 | NRZ 8b/10b | 2.5GT/s | ~256MB/s | ~1GB/s | ~2GB/s | ~4GB/s |
| 2.0 | NRZ 8b/10b | 5GT/s | ~512MB/s | ~2GB/s | ~4GB/s | ~8GB/s |
| 3.0 | NRZ 128b/130b | 8GT/s | ~1GB/s | ~4GB/s | ~8GB/s | ~16GB/s |
| 4.0 | NRZ 128b/130b | 16GT/s | ~2GB/s | ~8GB/s | ~16GB/s | ~32GB/s |
| 5.0 | NRZ 128b/130b | 32GT/s | ~4GB/s | ~16GB/s | ~32GB/s | ~64GB/s |
| 6.0 (expected in 2021) | PAM4 | 64GT/s | ~8GB/s | ~32GB/s | ~64GB/s | ~128GB/s |