The specification is not merely an overclock of the previous standard; it involves intricate engineering changes at the signal and protocol levels.
| Segment | Why PCIe 4.0 | | :--- | :--- | | | 8–16 GB/s per drive (vs 4 GB/s on PCIe 3.0) reduces read/write latency for AI/ML training. | | GPU Compute (AI/Graphics) | 64 GB/s bidirectional (x16) – essential for multi-GPU interconnects (e.g., NVLink over PCIe). | | High-speed Networking | 100 GbE NICs (25 GT/s ×4 lanes after encoding) fully supported. | | Storage Servers (SAS/SATA controllers) | More bandwidth for RAID arrays without bottlenecking CPU lanes. | | FPGA Accelerators | Xilinx Alveo, Intel Agilex – achieved 16 GT/s for streaming data acquisition. |
(Note: PCIe 5.0 and 6.0 base specs exist, but 4.0 remains the sweet spot for cost-effective bandwidth.)
PCI Express Base Specification Revision 4.0 Version 1.0 Release Date: October 5, 2017 (Final release by PCI-SIG) Code Name: PCIe 4.0 Supersedes: PCIe 3.1 / 3.0 Superseded by: PCIe 5.0 (May 2019)
