The "Memory Wall" has been a stubborn bottleneck in data center design: scaling memory has traditionally meant buying entire new CPUs just to unlock more memory channels — expensive, wasteful, and rigid.
Two interconnect standards are now solving this together:
- PCIe Gen 6 doubles raw bandwidth to 64 GT/s by switching from NRZ to PAM4 signaling, and introduces fixed 256-byte FLITs with built-in forward error correction to keep the noisier PAM4 signal reliable.
- CXL 3.1 sits on top of that PCIe 6 fabric to enable cache-coherent memory pooling, peer-to-peer memory sharing between GPUs (bypassing the CPU entirely), and fully disaggregated, fabric-attached memory across a rack.
The result is a shift away from monolithic, single-chassis servers toward composable infrastructure, where memory is a pooled, elastic resource instead of capacity stranded on one motherboard — a big deal for anyone running AI training, in-memory databases, or other memory-hungry workloads.
The full article covers the engineering in depth: why PAM4 was necessary, how the FLIT/FEC error-correction scheme works, CXL's three sub-protocols (CXL.io, CXL.cache, CXL.mem), and what tiered memory looks like for AI workloads in 2026.
👉 Read the full breakdown: https://www.leoservers.com/blogs/pcie-6-cxl-server-architecture/
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