Pci Express Base: Specification Revision 6.0

| Parameter | PCIe 5.0 | PCIe 6.0 | Improvement | | :--- | :--- | :--- | :--- | | | 32 GT/s | 64 GT/s | 2x | | x16 Bandwidth (bidirectional) | ~128 GB/s | ~256 GB/s | 2x | | x16 Bandwidth (unidirectional) | ~64 GB/s | ~128 GB/s | 2x | | Encoding Scheme | 128b/130b NRZ | PAM-4 + FLIT | New | | FEC | Optional (Replay) | Mandatory (Lightweight) | New | | Target Markets | Cloud, Enterprise AI | AI/ML, HPC, 800G Ethernet | Expanded |

PAM-4 signaling introduces more noise and a lower Signal-to-Noise Ratio (SNR) compared to NRZ, making the signal more susceptible to errors. To handle this, PCIe 6.0 introduced two auxiliary mechanisms to ensure reliability: pci express base specification revision 6.0