Samsung’s HBM3E breakthrough sets the stage for the real fight: HBM4 in 2026

Samsung has finally passed Nvidia’s HBM3E qualification, ending an 18 month slog that cost it design wins and credibility. It is a milestone that matters, but the real battle is HBM4. By the time vendors build 2026 accelerators, buyers will care less about who got in late on HBM3E and more about who can ship HBM4 at volume with the right thermals, power, and yields. That is where this cycle gets decided.

If you like semiconductor drama, HBM has been the main event for two years. The storyline is simple. Nvidia set the pace on GPU compute. HBM vendors set the ceiling on usable performance and power, because memory bandwidth decides whether you feed that compute or starve it. Through 2024 and most of 2025, SK hynix led the pack, Micron closed the gap, and Samsung could not get through Nvidia’s hoops. That part just changed.

South Korean outlets and international press report that Samsung’s 12 layer HBM3E finally cleared Nvidia’s qualification in September, after repeated thermal and reliability setbacks. Bloomberg and others noted the share price pop on the day. TrendForce framed it as the end of an 18 month delay that kept Samsung on the sideline for the most coveted AI sockets. Tom’s Hardware summed up the catch up moment neatly and added the important caveat. Yes, validation is done. No, it does not mean you immediately ship big volumes to Nvidia when rivals already have the allocation for current systems.

Qualifying HBM3E is the admission ticket. Winning 2026 is about HBM4. SK hynix told investors it has completed internal certification for HBM4 and is preparing mass production, with samples that started moving in March. There are notes that shipments begin in Q4 2025 and scale through 2026. Micron has said HBM4 mass production starts in 2026 with HBM4E targeted for 2027, and the company has been talking up performance and power advantages. Samsung is briefing that HBM4 samples go to Nvidia this month with eye on early 2026 validation and second half shipments if all goes to plan. Those trajectories define who gets written into Nvidia’s and other accelerator vendors’ 2026 BOMs.

Why HBM4, not HBM3E, calls the tune in 2026

HBM3E did the heavy lifting for 2025 systems. Think 12 layer stacks, taller packages, faster pin rates, and painful thermal density. The biggest lesson was not the headline bandwidth figure. It was how quickly you ran into system level constraints. Taller stacks are hotter and fussier. The interposer and package have to manage more heat in less area. Board designs need copper where there is no room for copper. VREG placement becomes an art project. That is before you deal with the ugly reality of yields on large multi die stacks.

HBM4 changes the conversation in three ways that matter to buyers:

Bandwidth and capacity per stack move up another tier. Public roadmaps and credible reporting point to roughly 2 TB per second per stack targets with 64 GB per stack configurations as a baseline for premium parts. Those numbers are not a JEDEC guarantee. They are where the competitive bar is being set for real products.
Logic die integration gets serious. SK hynix has been clear that customer specific logic dies are part of HBM4, which makes drop in replacement by a rival much harder. Once you co design a logic die that suits a vendor’s traffic patterns, timing, and error handling, you lock in that relationship for the life of the product.
Packaging and thermals change the win conditions. A fast HBM4 stack that browns out at temperature is a losing part. A slower stack that holds clocks at 90 C all day without spiking power is the real winner. This is why qualification tests from vendors like Nvidia are so brutal. They reflect system worst cases, not lab best cases.

Where the vendors stand right now

SK hynix. The incumbent leader earned that position. It shipped HBM3 and HBM3E early and in volume. It talks less than its rivals, but the signals are clean. Reuters reported internal HBM4 certification is complete and that the company is preparing mass production. The company said sample shipments began in March 2025, and other coverage notes that customer shipments begin late 2025 with volume expansion next year. There is a consistent theme from sell side notes and channel checks. Hynix has already sold out a lot of 2026 capacity. Nvidia asked Hynix to pull HBM4 forward by six months last year. The implication is simple. If you want HBM4 at volume in 2026, you are probably negotiating allocation at Hynix today, not next spring.

Micron. It spent much of 2024 and the first half of 2025 catching up on HBM3E and then started talking loudly about HBM4. TrendForce noted Micron’s plan for HBM4 mass production in 2026 and HBM4E in 2027 to 2028. Tom’s Hardware picked up the Micron and TSMC HBM4E collaboration, which suggests more custom packaging options and potentially tighter alignment with foundry processes. Investor letters and interviews suggest Micron expects to sell out 2026 HBM4 capacity. The marketing line is performance and power advantages. The engineering burden is proving that across full temperature and voltage ranges on real boards. If Micron holds those advantages at scale, it will gain share against Hynix.

Samsung. The bad news was public all year. Failing Nvidia tests hurts. It delays design wins. It feeds a narrative that your thermals are not under control. Getting through HBM3E qualification now is more than face saving. It is a prerequisite for HBM4 credibility. Korean press and international outlets say HBM4 samples go to Nvidia this month, with early 2026 validation targeted and second half shipments if yields hold. Samsung can move quickly when the engineering aligns. What it cannot do is rewrite capacity overnight. It enters 2026 as the third supplier by allocation even if it can ship. The opportunity is to over deliver on thermals and yields and take incremental share as customers derisk multi vendor strategies.

Qualification is not a rubber stamp

Nvidia’s qualification is famous for a reason. It tests worst case steady state, cycling, and noise scenarios that make HBM stacks cry. If a stack passes and then derates after 500 hours at temperature, it did not pass. If power delivery sidebands ring the wrong way at a few MHz offsets, it did not pass. This is not box ticking. It is survival of the fittest in a very hot, very cramped package.

Three practical points explain why buyers care more about qualification than about pretty lab slides:

HBM is now the thermal hotspot, not just the GPU. The die stack is tall. The heat has fewer exits. If your top stack degrades the GPU boost by 100 to 150 MHz because the board has to pull power and fan curves spike, the entire system loses throughput. Customers notice.
HBM4 logic dies bring custom behaviors. Better refresh schemes, error management, and timing tweaks move real world bandwidth and latency by double digit percentages in heavy inference workloads. Qualification checks those behaviors against GPU traffic patterns that do not appear in vendor slide decks.
Yields and rework define gross margin. A perfect spec with poor yields is a charity project. Qualification puts a number on how often stacks fall out under stress. That number drives how many good boards you ship per wafer and what your cost per good gigabyte really is.

What HBM4 changes on the board

HBM4 is not just a speed bump. It changes board planning, power budgets, and even datacenter layout choices. A few specifics that matter for system planners and reviewers:

Pin rates and signal integrity push the package harder. Getting 2 TB per second out of a stack requires clean signal paths and very strict impedance control. Expect more attention to interposer design, redistribution layers, and decoupling strategies that keep eye diagrams clean under heavy load.
Power delivery moves again. Higher sustainable bandwidth means more sustained current at the stack and at the board level. VRM topologies move to meet low ripple targets while keeping efficiency high at elevated temperatures. The winners will show fewer throttling events under mixed workloads.
Thermal solutions get thicker, not thinner. You cannot cheat thermodynamics. Expect taller vapor chambers, denser fin stacks, and more aggressive TIM choices around the HBM footprints. Reliable pressure across the stack will matter more than headline TDP numbers.

Allocation, pricing, and why 2026 could be sold out early

HBM has been constrained for two cycles. That will not magically change in 2026. Everything we hear points to allocation discussions already locking in for next year. Blocks and Files reported that SK hynix has 2026 demand largely spoken for and that HBM4 shipments begin this quarter with scale up next year. Investor notes argue Micron expects to sell out its 2026 HBM4 capacity. Samsung is sending samples now, which is the first step to winning real allocation by mid year.

Pricing follows allocation. Expect blended HBM pricing to hold firm through 2026 unless a vendor suffers a yield hit that frees capacity or unless demand softens across AI accelerators. Neither looks likely at scale. Cloud buyers will continue to pay for systems that finish jobs faster per rack. HBM4 is the tax you pay for that outcome. Vendors know it.

If you are a system builder outside the cloud hyperscale tier, this matters because you come in second for allocation. It also means you should treat any vendor promises about ship dates and quantities with suspicion until you have confirmed delivery windows in writing.

Thermals and power: the boring details that decide winners

HBM is a thermal problem disguised as a memory problem. Thermal density on tall stacks forces engineers to trade voltage, refresh behavior, and retention against heat soak in a package that also contains a GPU that wants every watt it can get. The physics does not care about roadmaps.

Watch for these three failure modes in 2026 reviews and teardowns:

Silent derates after soak. Many stacks look fine in a 5 minute benchmark. The truth appears after 40 minutes of mixed load compute when power delivery warms up and signal noise increases. Look for boards that keep HBM clocks and GPU boost stable across an hour long run.
Thermal runaway at the top stack. If one stack runs 8 to 10 C hotter than its neighbors because of airflow shadows or TIM contact inconsistencies, the whole board will derate early. You will see it in long run logs as a periodic dip in both HBM and GPU clocks.
Voltage droop sensitivity. Boards that pass qualification with narrow margins will show performance variance rack to rack. Better designs hold performance across different PDNs and different data center power profiles.

Scorecard for 2026

Based on public reporting, vendor disclosures, and the behavior of past cycles, here is the conservative view as of mid November 2025:

SK hynix looks like the default HBM4 supplier for anyone who wants capacity in the first half of 2026. It has been first with samples, first with internal certification, and looks booked for the year. The risk is less about technology and more about how many customers it can satisfy without forcing delays.
Micron is the challenger with upside. It talks about performance and power advantages and has the TSMC partnership to support tight package integration. If real boards prove those claims and if allocation is there, Micron will pick up share at the expense of rivals. The risk is yield at volume on the tallest stacks.
Samsung is the recovery story. Passing HBM3E qualification matters because it resets perceptions. If HBM4 samples validate on time and thermal behavior is good, Samsung has a path to win incremental sockets in the second half of 2026. The risk is time. Every month counts when rivals are locking in BOMs now.

What this means for Nvidia, AMD, and everyone building 2026 accelerators

For Nvidia, the message is stable. Keep multiple HBM vendors validated and soften the risk of overreliance on any one supplier. Co design logic dies where it makes sense. Keep pressure on thermals and power behavior under long duration loads. Your biggest risk in 2026 is not a single slow stack. It is a slow system because the HBM4 did not hold its clocks.

For AMD, this is a window. A year ago, MI parts suffered because HBM supply was not in their favor. Samsung’s recovery and Micron’s 2026 plans create headroom outside Hynix, which gives AMD more room to price and place systems without pleading for allocation. It does not erase the reality that Nvidia will still take the lion’s share of early HBM4, but it helps.

For second tier accelerators and custom silicon projects, plan for tight HBM4 supply through 2026. That means sober power targets, honest thermal designs, and careful binning to keep performance stable on real racks. You do not win by quoting peak specs. You win by shipping product that holds frequency at 2 AM on a hot aisle.

Bottom line

Samsung passed the HBM3E test that mattered. Good. The 2026 race will be won on HBM4. SK hynix still leads, Micron has a credible plan and the right talking points, and Samsung has a shot to convert momentum into shipments if the engineering holds. Allocation will be tight, pricing will be firm, and the data center will continue to reward the boring designs that run fast every hour of the day.