$Amazon(AMZN.US) PCIe was built to connect peripherals to CPUs; single lanes are slow and lane counts are limited. With standard upgrades slow and lane aggregation constrained, why would AWS still choose PCIe?

The answer is simple: minimize complexity and ship fast. By sticking to an established standard, they avoid building a custom switch chip and can both sidestep Nvidia's premium and deliver quickly to anchor customer Anthropic. In short, deliverability, not peak competitiveness, comes first.

There are costs on both fronts. On cadence, PCIe advances roughly every three years vs. about two years for NVLink, leaving AWS a follower. On lane aggregation, backplane copper, connectors, and retimers (signal-conditioning chips) stack up, pushing up power and cost.

If the next gen still relies on PCIe Gen7, the bind could worsen. With no easy doubling from a new modulation scheme, only higher line rates remain, which multiplies stress on substrates and retimers.

Dolphin Research sees two paths for AWS. First, move to UALink by swapping in a UALink switch and aligning the protocol. Second, pivot to Nvidia's NVLink; AWS has already said Trn4 will support NVLink Fusion (the externally accessible version of NVLink).