PCI-SIG rounds out PCIe 6.0 standard with 128GB/s transfer rates
The organization that oversees the PCI standard has the PCIe 6.0 standard ready. The maximum bandwidth is doubled compared to PCIe 5.0. The first products that support the standard are expected to appear within twelve to eighteen months.
According to PCI-SIG, the 6.0 standard enables transfer speeds of up to 128GB/s when using 16 lanes, doubling that of PCIe 5.0. Initially, the higher speeds are especially useful for servers, as there is a continuous demand for more bandwidth in data centers, for AI and HPC applications, among other things. PCI-SIG reports to AnandTech that PCIe 6.0 will be deployed in commercial products within 12 to 18 months. These are expected to be products for the server market. Consumer products with support for the standard, such as SSDs, will follow at a later time. The use of PCIe 5.0 for SSDs is only just getting started.
To enable the doubling of the bandwidth, the PCIe 6.0 standard uses pulse-amplitude modulation 4, or pam4, with a flit, or a flow control unit. With this, the standard moves away from the non-return-to-zero technique, which has been used since version 1.0. The pam4 modulation uses four voltage levels to encode 2 bits of data. This leads to higher data transmission, but also makes the signal more fragile and is therefore accompanied by a higher bit error rate. To counter this, PCIe 6.0 uses a lightweight forward error correction technique, based on the probability of bit errors, using first bit error rate parameters.
In 2019, the organization already announced the PCIe 6.0 standard, with the expectation that the specification would be finalized in 2021. The intention is that a new standard with a double bandwidth will be released every three years. PCI-SIG says the standard is backwards compatible with all previous PCIe generations.
| 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 | Pam4 1b/1b (with flash encoding) | 64GT/s | ~8GB/s | ~32GB/s | ~64GB/s | ~128GB/s |