However, the spec introduces a subtle change: . For Gen4 to work reliably, the host and device must exchange preset coefficients before exiting reset. If you see a drive failing to train to Gen4, the PDF’s Link Equalization flowchart is your debug checklist. 4. Power Management: The L1.1 Substate Gen4 controllers consume more power than Gen3. Revision 4.0 updates the M.2 power management sequence to support L1.1 (ASPM) with lower exit latency.
Demystifying the PCIe M.2 Spec: A Deep Dive into Revision 4.0 Version 1.0 Pci Express M.2 Specification Revision 4.0 Version 1.0 Pdf
pcie-m2-specification-revision-4-0-version-1-0 However, the spec introduces a subtle change: