We’d like to thank DG Matrix, Novos Power, and Aran Industries for their contributions and insights during the preparation of this deep dive.
Introduction: Welcome to the Power Chain Roller CoasterAcross every major industry conference in the first half of 2026, our research team kept walking past the same scene: a booth ten or fifteen people deep, leaning in to catch every word from another datacenter equipment messiah preaching the gospel of 800VDC. The pitch was the same every time. 800VDC is about to change the electrical infrastructure of the datacenter.
Every architectural shift looked excessive at first. Operators spent decades keeping water and leaks out of the data hall, then GPU thermal density made running coolant right up against the precious silicon unavoidable. Each shift happened anyway, because physics and the economics of compute do not negotiate. 800VDC is next, and the logic is the same. Tokens per watt are what matters.

Source: Nvidia, InferenceX
As GPU clusters become increasingly dense, with Kyber Ultra approaching 660kW per rack, the physics start to break down. Resistive losses scale with current squared, and at these power levels copper mass and thermal envelope exceed what fits inside a rack. Moving to 800VDC eliminates conversion stages, reduces resistive losses, and cuts facility-level power consumption by ~5%. At 1GW of IT load, that is over 50MW of continuous savings, tens of millions in annual electricity costs, or new compute capacity unlocked. For all the inference-king proponents out there, 800VDC is a transition forced by physics and motivated by system economics.
We have been tracking this transition through our InferenceX and Industrials Models, which provide a bottom-up view of where efficiency gains materialize and which equipment categories absorb the disruption. The Industrials Model includes a dedicated 800VDC module, building up from individual accelerator architectures to a top-down view of 800VDC penetration, MW adoption, and market sizing for equipment like the power sidecar and Solid-State Transformers (SSTs).
Source: SemiAnalysis Industrials Model
This deep dive traces the transition phase by phase: from the sidecar retrofit, through faciliy-level DC distribution, to the SST endgame. For each phase, we analyze the BoM and map the changes in equipment content/MW, what survives, what gets redesigned, and what gets eliminated.
The 800VDC revolution is set to dramatically change the revenue trajectory of certain suppliers. We’ve been tracking winners and losers for over a year in Industrials Model, which estimates the BoM for 20+ different datacenter designs broken down into 70+ equipment types and lays out the impact for 500+ suppliers. It is built on our industry-leading Datacenter Model which forecasts quarter-by-quarter MWs for 6000+ datacenters and anticipates design changes.
This has enabled us to successfully call out both winners, and companies inaccurately pictured as losers by the market, before anyone else. If you are wondering whether UPS systems have a place in upcoming 800VDC distribution, what is the market opportunity for SSTs, or which suppliers are leading this transition, stick with us.
Source: SemiAnalysis Industrials Model
Part 1 of this 800VDC Revolution series covers datacenter layout and equipment implications. Part 2 will focus on power electronics and the semiconductor revolution underneath it.
Understanding The Basics: What is 800VDC and Why It’s InevitableAt its simplest, 800VDC in this context means distributing power at ~800 volts direct current through the data hall or row and into the rack, then stepping it down near the compute. The number 800 is not arbitrary, but a voltage high enough to materially reduce current (and therefore copper loss and thermal burden) while remaining within the broad regulatory and product-safety classification of “low-voltage DC” in many jurisdictions. For context, EU rules around the Low Voltage Directive scope reference DC equipment ratings up to 1,500 V DC (and AC up to 1,000 V).
Current datacenter electrical architectures generally rely on AC distribution at the facility level. Datacenters today use three-phase AC at 415V or 480V, and the topology relies on conventional UPS architectures before distributing 48-54V DC within the rack.
This works at today’s rack power levels, but starts to fail as rack densities in the next two years approach ~600 kW+, for several reasons:
Copper becomes unmanageable at 48–54 V. A 1 MW rack at 48–54 VDC needs ~200 kg of copper busbars. At 1 GW scale, that’s hundreds of tons of copper — brutal on cost, weight, installation complexity, and routing space.
Source: Microsoft
Power shelves crowd out compute. Today’s NVL72 racks already use up to 8 power shelves. At Kyber-class rack power, a 48–54V approach would require ~64U-equivalent of power hardware, effectiviely an entire rack, leaving no volume for compute.
Current becomes the real limiter. Delivering 600 kW at 48–54 V implies ~12,500A. At 800 V, that drops to ~750 A (~16.7× less), enabling dramatically smaller conductors/busbars and far lower thermal stress. If conductor resistance were held constant, I²R losses fall ~278×, so in practice you shrink copper and “buy” size/weight reductions.
Conversion losses compound and hurt reliability. Stacked AC-to-DC and DC-to-DC stages reduce end-to-end efficiency, increase heat, and introduce failure points, raising cooling loads, downtime risk, and maintenance costs.
At the end of the day, 800VDC is the physics enabler for 2,300W TDP chips and 600kW racks, and those 600kW racks are the direct consequence of the push for density, because density is what drives cost per token down. Cost per token is dictated by the size of the scale-up world you can build at full NVLink bandwidth: bigger domains mean wider Expert Parallelism (EP) / Tensor Parallelism (TP), MoE routing on NVLink rather than scale-out, and less serialization across decode. As we laid out in our Vera Rubin Deep Dive and GTC 2026 pieces, Nvidia’s design rule is to pack compute tightly enough that copper reaches everything in the rack. Reiner Pope made this point cleanly on our friend Dwarkesh’s podcast a few weeks ago, indicating that a single rack bounds the size of the expert layer you can build, because the moment an all-to-all crosses a rack boundary, it falls onto a scale-out fabric that is roughly eight times slower than NVLink.
Bigger scale-up worlds mean denser racks, denser racks mean 600kW envelopes, and 800VDC is what makes those envelopes possible.
Source: SemiAnalysis AI Networking Model
The Four Chapters of the HVDC TransitionThe move to 800VDC is a complex metamorphosis that rewrites the entire electrical architecture, introduces new safety standards, requires new regulatory frameworks, and, most importantly, forces operators to make very different strategic choices about when to walk away from their legacy AC distribution.
Source: SemiAnalysis
We frame the 800VDC transition as progressing through four distinct phases. Phases 1 and 2, starting in late 2026 / early 2027, retrofit the existing AC distribution into 800VDC at the rack level via the power rack. Phase 1 is the early-mover stage, driven by hyperscalers willing to pay up for future-proofing and efficiency gains. Phase 2 kicks in once 800VDC-native systems begin shipping at volume. Phase 3 rewrites the electrical architecture itself, taking 800VDC distribution facility-wide. Phase 4 is the end state, built around new pieces of equipment that promise to render much of today’s electrical stack obsolete.
Source: SemiAnalysis Industrials Model
The result is a progressive adoption curve for 800VDC. We expect total incremental capacity powered by 800VDC to reach ~39GW by 2030. Through Phases 1 and 2, all addressable capacity is served by sidecars, since the underlying facility is still AC-distributed and the conversion happens at the power rack. The mix inflects in 2029 as facility-level HVDC distribution becomes viable and the first 800VDC-native sites come online, shifting the conversion stage upstream from the rack to the SST or MV rectifier.
Source: SemiAnalysis Industrials Model
Before diving into how the datacenter layout changes, we encourage readers to revisit Part 1 of our datacenter anatomy series, which explains many of the core concepts behind datacenter electrical equipment.
Phase 1 (2026/2027): The White Space RetrofitSource: SemiAnalysis Industrials Model
The HVDC journey begins primarily with two operators, Google and Meta. Both have been pushing their 800VDC architectures through the OCP working groups for over 18 months, most visibly with the Mt. Diablo reference design, first announced in October 2024 and published as an open specification in May 2025. Neither is being forced into the transition, but they are doing it to take a leading position in the upcoming shift and because they want to squeeze every megawatt and every point of efficiency out of their existing power chain before the rest of the market is forced to catch up.
This matters because 800VDC is not yet a hard requirement. The chip generations ramping in late 2026 and 2027, like Vera Rubin NVL72, top out at rack densities of 180-220kW. Three-phase AC can still deliver that without hitting the physical limits of conductor sizing or distribution losses. Phase 1 is therefore voluntary future-proofing, not a forced response to a hardware constraint.
This initial phase kicks off the “White Space Retrofit” era. New HVDC hardware, primarily a row-level cabinet called the HVDC power rack, layers on top of existing white space infrastructure rather than replacing it. The datacenter’s electrical backbone stays intact. Same transformers, same UPS, same switchgear, same ATS.
Power Flow Overview with HVDC Power RackAt the facility level, Medium-voltage AC enters the grey space and is stepped down via transformer to 415V or 480V three-phase AC. That feeds into a UPS, which performs double conversion (AC-DC-AC), then outputs 415V AC. AC is then distributed through the data hall via busway. So far, this is the traditional power flow we have extensively covered in previous articles.
The change occurs when we get closer to the IT racks. Instead of feeding 415V directly into in-rack power supply units, the AC feed now terminates at a standalone 42U cabinet named the HVDC power rack deployed at the row level.
Source: SemiAnalysis
The rack receives AC from the overhead busway and outputs 800VDC through cable to adjacent IT racks. Inside, it performs three jobs: rectification of 415V AC to 800VDC, BBU modules for ride-through during outages, and optionally, capacitor shelves for transient buffering during GPU load spikes.
In a Nutshell: The Power RackIt is worth looking in more detail into the building block that underpins Phases 1 and 2 of the 800VDC transition: the disaggregated power rack. This is a dedicated rack that consolidates AC-to-DC rectification, energy storage (BBU and/or capacitor bank), and power management into a single unit, freeing the compute rack to be entirely dedicated to GPUs, networking, and cooling. Microsoft’s Mt Diablo project originated the concept; the OCP Diablo 400 specification, co-authored by Google, Meta, and Microsoft, standardizes it.
Key components that are commonly found in a sidecar power rack:
Source: Rittal
Source: SemiAnalysis
But the sidecar concept did not emerge fully formed. It evolved through several OCP rack and power specification versions. The earlier iterations (ORv2 at 12V, ORv3 at 48V, and the HPR V1/V2 variants that pushed single-rack 48V designs up to ~190 kW with liquid-cooled busbars and upgraded 72 kW power shelves) are covered in our Datacenter Anatomy series. Here we focus on the versions directly relevant to 800VDC: the disaggregated sidecar designs where the voltage transition occurs.
Source: OCP
ORv3 HPR V3: The Disaggregation Threshold (50V Sidecar, up to 300 kW)HPR V3 is really where power and compute separate into distinct racks, the genesis of the “sidecar” concept. PSU and BBU shelves move into a dedicated 50VDC side power rack connected to the IT rack through horizontal busbars at the top and bottom of both. Both remain ORv3 HPR standard form factor. Power capacity tops out at 300 kW, limited by the horizontal crosslinks and the air-cooled vertical busbar inside the power rack.
Source: OCP
The insight is putting power conversion hardware in a rack optimized for power, with appropriate cooling, safety, and serviceability, rather than cramming it into a rack optimized for compute. The V3 power rack can be serviced independently, shrinking the blast radius of power-side failures. But V3 still distributes at 50VDC, which means busbar currents remain high (6,000A at 300 kW) and the crosslinks become the bottleneck.
Source: SemiAnalysis
This persists today. Even the VR NVL72 rack, when fed by an HVDC power rack at 800VDC (Nvidia spec) or ±400VDC (OCP spec), still distributes internally over a 50V busbar. A DC-DC power shelf inside the rack steps the high-voltage DC down to 50VDC before it reaches the compute trays. At the far end, VRMs on the GPU board convert from 50V to sub-1V.
We have more detailed power and architecture details in our VR NVL72 Component BoM and Power Budget Model.
ORv3 HPR V4: HVDC Sidecar at +/-400VDC (up to 800 kW)HPR V4 is the version that bridges the OCP HPR lineage into the HVDC era. It makes two critical changes: the voltage steps up from 50VDC to +/-400VDC (800V total), and the busbar-based crosslink is replaced with discrete power cables.
Architecture: PSU and BBU shelves move into a +/-400VDC side power rack, which also houses AC input and DC output PDUs
Power delivery: The power rack connects to the IT rack through 16x 50 kW HVDC cables (replacing the horizontal busbars of V3), each carrying +/-400VDC
Power capacity: Up to 800 kW maximum. If capacitor-based energy storage (CBUs) occupies half the BBU slots, effective capacity drops to ~400 kW
AC input: 200A single conductor wire from tap boxes
Form factor: Same ORv3 HPR rack dimensions as V3
Why cables instead of busbars: At the power levels V4 targets (400-800 kW), the horizontal busbar crosslinks from V3 become current-limited. Replacing them with discrete cables allows each cable to be independently routed, fused, and managed, and eliminates the single-point busbar as a thermal and mechanical constraint
V4 effectively represents the “pre-Diablo” state of HVDC sidecar design, developed primarily by Meta’s rack and power team. It proved the concept of disaggregated HVDC power delivery but was not yet a multi-vendor, multi-hyperscaler specification.
Source: Meta
The Diablo 400 Specification: Standardizing the HVDC SidecarThe Diablo 400 specification (named after Mt Diablo, Microsoft’s original internal project name) formalizes and standardizes the HVDC sidecar concept that HPR V4 pioneered. Co-authored by Google, Meta, and Microsoft, Diablo 400 was released as a draft specification (v0.5.2) in May 2025, with a subsequent v0.7.0 revision following industry feedback.
What Diablo 400 standardizes that HPR V4 did not:
Multi-vendor interoperability: Standardized electrical and mechanical interfaces so that PSU shelves from Delta, power management from Advanced Energy, busbars from TE Connectivity, and BBUs from multiple suppliers can all work together in a single rack
Dual voltage support: The base specification defines +/-400VDC bipolar as the standard configuration (3-wire: +400V, -400V, and Common/Midpoint/Return at the rectifier shelf output), with 800VDC monopolar as an explicit design option (2-wire: 800VDC and Return, safety-isolated from PE ground)
Power range: 100 kW to 1 MW per IT rack
PSU design: 3-phase AC input, +/-400VDC output. PSU modules are front-of-rack accessible, hot-swappable, and hot-pluggable, with droop and active current sharing between PSUs and power shelves
Cable spec: Voltage drop budget of 0.1% at 5m cable length for output cables between power rack and IT rack
Holdup time: Minimum 20 ms without energy storage at 100% loading; distributed holdup acceptable between the AC/DC PSU in the Diablo 400 rack and downstream DC/DC converters located outside the rack
Mechanical: Sliding shelves for push-in/pull-out of large building blocks (e.g., 4OU BBU), blind-mate connectors with static rail/sliding rails for PSU/BBU/CBU hot-swap
Seven standardization areas: Connectivity, power rack form factor, AC-DC PSU topology, DC-DC modules, redundancy architecture (single/dual feed, N+x), safety standards for HVDC and liquid-cooled systems, and data/power management backplane
The choice of 400VDC as the nominal voltage was deliberate. As Google’s engineers stated at OCP EMEA 2025: “selecting 400 VDC as the nominal voltage allows us to leverage the supply chain established by electric vehicles, for greater economies of scale, more efficient manufacturing, and improved quality and scale.” In the bipolar configuration, each individual rail sits only 400V from the grounded midpoint, keeping the system within the voltage range where mature EV-grade power electronics (650V GaN FETs, 400V-class capacitors, connectors, and fuses) can be used directly.
No One-Size-Fits-AllThere is no one-size-fits-all 800VDC power rack. Yes, Diablo 400 provides a shared base specs, but the reality on the ground is fragmented. Nvidia sits entirely outside it and is developing a monopolar 800V reference design at 660kW, with air-cooled samples and production in mid-2026, and a liquid-cooled VR Ultra variant sampling in late-2026.
Even within Diablo 400, the three co-authors diverge meaningfully. Meta runs 600-800kW with 50kW HVDC output cables and 8x 200A AC input whips. Google push to 900Kw by reallocating rack space from BBU and supercap slots to PSUs, run 100kW output cables, and need 12 AC whips at the 1.1MW roofline. Amazon’s design lands at 800kW on ±400V. Microsoft co-authored the spec but we believe they are making slower progress.
Besides, an alternative sidecar topology uses an LV-input SST in place of the conventional rectifier-plus-PSU stack, like DG Matrix’s Interport Cell Series.
Source: DG Matrix
The cost of the power rackThe HVDC power rack is the headline new-equipment cost in the early retrofit phases. We estimate the ASP for the Power Rack to reach $400-500k per unit, roughly 10x the ~$40k ASP of standard AC power-rack equipment. On a deployed-MW basis, that lands near $500k/MW.
Source: SemiAnalysis Industrials Model
The Sidecar Market Opportunity and TAM sizingIn our SemiAnalysis Industrials Model, we size the 800VDC equipment TAM, specifically for the sidecar (power rack) and Solid State Transformer (SST), by applying this phase-by-phase adoption timelines to incremental datacenter capacity build and doing a chip-by-chip SKU calculation.
We expect sidecar TAM to peak at ~$11B in 2028 before declining as facility-level 800VDC takes share in Phase 3. We assume a power rack content of $0.5M/MW.
Source: SemiAnalysis Industrials Model
Phase 1 SummaryThe white-space retrofit represents a clear cost uplift in electrical content/MW versus current architectures, because Phase 1 essentially deletes nothing. We estimate the delta at roughly +$400-500k/MW, with the HVDC power rack accounting for the large majority.
Source: SemiAnalysis Industrials Model
Phase 2 (2027/2028): The Turning Point Comes with 800VDC-Native ComputeSource: SemiAnalysis Industrials Model
Phase 1 was the start of the retrofit era. The real inflection point comes with the arrival of 800VDC-native systems. At that point, 800VDC stops being a future-proofing pilot and becomes a mandatory transition forced by physics and rack density. Operators electrifying the Kyber Rack have no AC fallback at the rack inlet, and we expect 800VDC penetration to spike sharply in this window. Because 800VDC-native silicon will land before facility-level 800VDC distribution is ready, the retrofit phase persists.
So