AWS Trainium3 Deep Dive – a Potential Challenger Approaching
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The AI chip landscape is heating up with AWS Trainium3 on the horizon, sparking debate about its potential to challenge NVIDIA's dominance. While some commenters, like klysm, argue that Trainium3 won't be a legitimate threat without massive software investment, others, such as stogot, point out that AWS is already making significant strides in software strategy, including open-sourcing a new PyTorch backend. The discussion reveals a mix of skepticism and optimism, with some, like mrlongroots, noting that hyperscalers don't need to achieve parity with NVIDIA to be successful, and others, like bri3d, suggesting that the value of commodity software stack compatibility is being overstated. As the conversation unfolds, it becomes clear that the real question is whether AWS can execute on its ambitious plans and capitalize on the growing demand for custom AI chips.
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Dec 4, 2025 at 2:19 PM EST
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> In fact, they are conducting a massive, multi-phase shift in software strategy. Phase 1 is releasing and open sourcing a new native PyTorch backend. They will also be open sourcing the compiler for their kernel language called “NKI” (Neuron Kernal Interface) and their kernel and communication libraries matmul and ML ops (analogous to NCCL, cuBLAS, cuDNN, Aten Ops). Phase 2 consists of open sourcing their XLA graph compiler and JAX software stack.
> By open sourcing most of their software stack, AWS will help broaden adoption and kick-start an open developer ecosystem. We believe the CUDA Moat isn’t constructed by the Nvidia engineers that built the castle, but by the millions of external developers that dig the moat around that castle by contributing to the CUDA ecosystem. AWS has internalized this and is pursuing the exact same strategy.
With Alchip, Amazon is working on "more economical design, foundry and backend support" for its upcoming chip programs, according to Acree.
https://www.morningstar.com/news/marketwatch/20251208112/mar...
Amazon has all the resources needed to write their own backends to several ML software or even drop-in API replacements.
Eventually economics win: where margins are high competition appears and in time margins get thinner and competition starts disappearing again, it's a cycle.
AWS can make it seamless, so you can run open source models on their hardware.
See their ARM based instances, you rarely notice you are running on ARM, when using Lambda, k8s, fargate and others
Turns out multi-billion dollar software companies can deal with the enormous software investment
I do think AWS need to improve their software to capture more downmarket traction, but my understanding is that even Trainium2 with virtually no public support was financially successful for Anthropic as well as for scaling AWS Bedrock workloads.
Ease of optimization at the architecture level is what matters at the bleeding edge; a pure-AI organization will have teams of optimization and compiler engineers who will be mining for tricks to optimize the hardware.
Until Amazon/AWS to invests in making the developer experience less crap, this will continue to be an interesting side project.
It doesn't have a lot of ports and certainly not enough NTB to be useful as a switch, but man, wild to me than an AMD Epyc core has 128 lanes of PCIe and that switch chips are struggling to match even a basic server's worth of net bandwidth.