@SemiAnalysis — Investing Ideas, Posts & Market Views

@SemiAnalysis20 hours ago

NVIDIA LPU supports 3 types of disaggregated inferencing:

1. Rubin Prefill + LPU Decode for the fastest interactivity

2. Rubin Prefill + Rubin Decode Attention + LPU Decode FFN for the middle of the curve

3. Rubin Prefill + Rubin Decode Verification + LPU Drafter for the middle-left of the curve

For low interactivity, raw Rubin still takes the win. Looking forward to seeing Rubin + LPU performance curves on open-source agentic benchmarks like AgentX.

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@SemiAnalysisAug 27 at 01:06 PM

BREAKING NEWS: AMD middle managers are wasting over 20+ engineers’ time trying to grow their fiefdoms & get promotions on a useless side project called their “ATOM Inference Engine,” instead of spending that effort on inference engines that actual customers like Meta/xAI actually use, such as SGLang/vLLM.

Dozens of AMD engineers, including principal engineers and AMD Fellows, have reached out to us privately about how, due to office politics and backing from a subset of middle managers at AMD, they are prevented from talking internally about their concerns over middle management wasting 20+ full-time engineers’ time on a side project with basically no customers. The engineers on this side project are 10x engineers and instead should be working on customer engines like vLLM/SGLang.

The middle managers will try to cope by referencing the singular customer that uses it in prod, Alibaba on Qwen, but when digging deeper, it is just a side-business enterprise unit deploying ATOM in a limited capacity instead of the main Qwen business unit.

It is incredibly disrespectful to AMD engineers for AMD management to pull resources & limited internal GPU R&D dev clusters away from engineers supporting customers on production engines like vLLM/SGLang to spend them on growing their fiefdoms & playing office politics.

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@SemiAnalysisAug 24 at 05:06 PM

We have written extensively about how forecasted AI IT and AI Datacenter capex will drive a record breaking amount of funding needs and an unprecedented growth in debt issuance.

By the end of this year, cumulative lifetime AI Capex will have reached nearly $3T USD and we expect this number to grow to $11T+ by the late 2020s, with total outstanding AI Debt reaching $7T+. 2026 will be the first year in which AI Debt Financing becomes the second largest asset related debt market, after only the US Residential Mortgage Market. It is also the last year in which total AI related debt issuance will be less than 10% of total US Fixed Income Issuance (this includes state and federal bonds, MBS/RMBS, corporate bonds, agency, muni and ABS). (1/3)🧵

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@SemiAnalysisAug 15 at 02:06 PM

Great to see @dotsstudioai from the popular Chinese social media app (@xiaohongshu, known as RedNote in English) join the open-weight community! ❤️ The team is still trying it out for day-to-day use to see the actual quality of the model or if it is eval maxed.

Regardless, it is always great to see another company join the open community!

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@SemiAnalysisAug 10 at 09:06 PM

How do different operating systems and microarchitectures affect the end user experience with agentic AI?

We looked through 2.91M actual Claude tool use responses to find out.

By our data, it appears that Linux is typically faster than Windows by a factor of about 3x in execution of shell commands. (1/2)🧵

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@SemiAnalysisAug 10 at 05:06 PM

NPO presents an interim solution under the transition from pluggable to true CPO. NPO has certain benefits over CPO that bypass current production and reliability challenge of CPO, while maintaining most of the benefits CPO provide.

Pros:

🟠 Better serviceability (field replacable)

🟠 Lower blast radius (blast radius limited to the individual NPO module)

🟠 Easier assembly (Optical Engine are packaged separately from the Switch ASIC/XPU)

Let's look at how NPO differentiate from CPO architecturally. (1/3)🧵

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@SemiAnalysisAug 9 at 05:06 PM

THIS IS AN ENGAGEMENT BAIT & HOT TAKE 🚨Percy Jackson is a better movie than Odyssey in terms of storytelling. Odyssey is one of Christopher Nolan's worst films. The storytelling was so poor that they had to distract viewers by adding IMAX 70mm cameras.

Also FYI for those of y’all who did not have the luxury of watching in IMAX 70mm film, you are missing 40% of the movie.

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@SemiAnalysisAug 6 at 11:22 PM

Most of AMD’s top 10x AI engineers are in Shanghai 🔥 This includes AMD’s MoRI collective and UMBP KV-cache offloading and pooling team, its disaggregated-applications forward-deployed engineering team, and other AMD teams that understand how to approach inference engineering from first principles.

Many of the most important components of the ROCm software stack are built in mainland China.

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@SemiAnalysisAug 6 at 12:02 AM

The datacenter fight in the US has so far run through county boards and city councils. But that ended on July 14, when Gov Kathy Hochul signed Executive Order 62 and New York became the first state to implement a datacenter moratorium. (1/5)🧵

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@SemiAnalysisAug 5 at 01:26 AM

SemiAnalysis Datacenter team tracks all dc sites. Datacenter team started noticing new builds missing the gensets. Datacenter team checked the Industrials Model and now tracks 15GW+ of capacity with no gensets, no central UPS, or neither. (1/3)🧵

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@SemiAnalysisAug 4 at 04:56 PM

How often does Claude use tools?

We looked through 2.27M Claude responses we collected to find out.

The Opus models show a clear downward trend in tool calls from Opus 4.6 to Opus 4.8. However, Fable 5 stands out against that pattern, averaging 1.00 tool calls per response compared with 0.76 for Opus 4.8 and 0.79 for Opus 5. (1/2)🧵

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@SemiAnalysisAug 4 at 02:06 AM

We believe the MI455 is the first known chip to ship with active Local Silicon Interconnect (LSI) bridges, the chiplet-to-chiplet links inside a CoWoS-L package.

In CoWoS-L's short history, those bridges have always been passive: wiring and capacitors, nothing more. Active LSIs carry real circuitry. At ISSCC 2026, TSMC demoed active bridges with a low-power repeater that regenerates signals mid-channel.

Why it matters: once the bridge shares the signal-integrity burden, the PHYs on the top dies can shrink meaningfully at near-zero energy cost, reclaiming leading-edge silicon and shoreline for compute and memory.

The giveaway that this is a shipping product rather than a research vehicle: the interposer TSMC showed matches the MI455 exactly. Two base dies, twelve HBM4 stacks, two IO dies.

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@SemiAnalysisAug 1 at 05:06 PM

AMD MI355X vLLM HAS BEATEN B200 vLLM ON KIMI K2.5 (THE SAME MODEL ARCH AS XAI CURSOR COMPOSER 2.5)🚀🚨

This uses upstream AMD kernels from the @GPU_MODE community. We explain below 👇 1/6🧵

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@SemiAnalysisJul 31 at 05:06 PM

Indium Phosphide (InP) LASERs are suddenly catching everyone's interest since it suddenly became one of the more strategic components in computing. As optical connectivity moves ever closer to the package, every optical engine and laser source inevitably runs on InP LASERs. But supply isn't keeping up with demand, particularly for Continuous Wave (CW) Distributed Feedback (DFB) LASERs which enable near-package optical connectivity. (1/2)🧵

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@SemiAnalysisJul 30 at 01:06 PM

Ever wonder why PCB folks throw around "M8" or "M9" like a spec sheet magic word?

The "M" traces back to Panasonic's Megtron series — long the benchmark for low-loss, high-speed copper clad laminate (CCL).

Each generation from Megtron 4 to 8 progressively lowered the dissipation factor (Df), meaning less signal loss at high frequencies.

Because Megtron set the bar, it became industry shorthand for a performance tier rather than a Panasonic-exclusive part number. Say "M8 grade" today, and it simply means "meets Megtron 8 electrical specs" — whether it's made by Panasonic, EMC, or Doosan.

As AI servers demand ever-higher SerDes speeds, high-tier CCL has become the critical bottleneck material. That makes it one of the tightest, fastest-growing segments in the entire hardware supply chain.

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@SemiAnalysisJul 30 at 02:04 AM

GREAT WORK BY @GPU_MODE 🚨 FOR LAUNCHING THE $1.1mil AMD KERNEL HACKATHON.

The GPUMODE Readonflow Team’s kernels improved end-to-end MI355X performance by over 2x. We explain the optimizations below. 1/4🧵

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@SemiAnalysisJul 29 at 10:14 PM

The Wild Wild West Of LEGO Datacenters

Everyone Says They're Modular,

Do The Vendor Claims Hold Up?

Zuck's Tents, AWS's Houdini,

60GW+ Modular Capacity Tracked,

Full Vendor Landscape Mapping,

Vertiv's 2x Content Uplift Per MW

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@SemiAnalysisJul 27 at 09:04 PM

AMD's warrant deals with OpenAI and Meta usually get described as equity sweeteners. Run the math, and these look more like a rebate that matches the price of the compute itself, with up to a 105% discount for OpenAI. (1/3)🧵

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@SemiAnalysisJul 23 at 02:45 AM

Vera Rubin NVL72 vs GB200 NVL72? Inference TCO & Architecture Analysis:

Rubin LUT Based Tensor Core, Feynman,

Rack Scale, Perf Per MegaWatt, Perf Per Dollar,

Software Improvements, Public Rubin Software,

PyTorch, vLLM, OpenAI Triton

Read Now:

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@SemiAnalysisJul 21 at 07:52 PM

ALERT🚨🚨: META's CUSTOM AMD MI400-series chip will be half the size of a normal MI455X chip. It is "optimized" for recsys workloads and $/Memory Bandwidth. It will use ~144GB of HBM instead of 432GB. We break it down below👇️ 1/7🧵

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@SemiAnalysisJul 21 at 01:32 PM

Datacenters have always kept reciprocating engines on site as emergency standby, kicking in when the grid drops and running a handful of hours a year. That role is changing, as recips are increasingly being repurposed to prime power, energizing datacenters around the clock. We estimate that recip OEMs (e.g., Caterpillar, INNIO, Cummins) have been contracted to supply ~1 GW of BTM power this year, and 4+ GW in each of 2027 and 2028. Our SemiAnalysis Energy Model tracks these BTM contracts OEM-by-OEM, project-by-project. Yet, that is dwarfed by the opportunity to come. (1/3)🧵

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@SemiAnalysisJul 20 at 08:21 PM

Great work by the AMD @sgl_project team on enabling nightly disaggregated serving CI to improve code quality! It has already caught and prevented 2 massive bugs from reaching customers, as we explained before 👇️ 1/7🧵

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@SemiAnalysisJul 17 at 10:51 PM

Similar to the panic over DeepSeek R1, some uneducated people think Kimi K3’s use of linear attention (KDA) is bad for NVIDIA, HBM, DRAM, and networking because it has relatively lower KV-cache requirements. The opposite is true, and we explain why below. 👇️ 1/8🧵

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@SemiAnalysisJul 17 at 02:01 PM

BREAKING: Broadcom is diversifying away from long-time foundry partner TSMC. Lego will be the new manufacturing partner for Broadcom's flagship hyperscaler ASIC products in 2028. Broadcom President of Semiconductor Solutions, Charlie Kawwas, has already showed off package samples at RAISE Summit in Paris last week. With TSMC supply constrained, customers are alternative sources of chip supply from unexpected places. One of the major differentiators Lego brings is industry leading defect repair, "plug and play" chiplet interoperability, as well as built in self-alignment technology for 3D stacking. Mattel and Hasbro were also under consideration, but Lego's proven track record won out in the end. We have ordered multiple Millennium Falcon Sets set to our Portland teardown lab for competitive teardown analysis.