Inside a current AI server rack, electricity arrives as alternating current, is rectified, stepped down and pushed along a 54-volt busbar before a final conversion at the graphics processor. NVIDIA's proposed replacement carries 800 volts of direct current from the row into the rack itself, stripping out conversion stages and a great deal of copper. It is a genuine architectural change, and a small group of American component makers is positioned for it.

It is also, on every one of these companies' own guidance, a 2027 event. Navitas Semiconductor, which makes gallium-nitride and silicon-carbide power chips, told investors on 27 July that the 800-volt sidecar rack inflection arrives around mid-2027. Vicor, an Andover, Massachusetts maker of modular DC-DC power converters, guides production of its second-generation vertical power delivery modules to late in the fourth quarter of 2027. Ideal Power, a 17-person Austin company developing a bi-directional solid-state switch, tied its pipeline explicitly to "800-volt DC power architecture adoption beginning H2 2027."

What is actually in the numbers

Bel Fuse, a Jersey City manufacturer of magnetics, circuit protection and board-mount power modules, is the one unambiguous grower. Second-quarter revenue rose 25.2% to $210.7m, gross margin widened 120 basis points to 39.9%, and operating income grew 47.4% — faster than sales. It has now reported six straight quarters of positive book-to-bill. But its biggest single contributor was aerospace and defense, where sales rose 28.4% to $66.5m, ahead of the roughly $58m data-center line. The data business did grow 55% year on year, helped by the March acquisition of connector maker dataMate. Bel guides the third quarter to $205m-225m.

Ultralife, an Industrials-classified maker of lithium batteries and military communications gear with a market value near $125m, saw revenue fall 1.3% to $47.9m as its battery segment shrank on oil-and-gas weakness. Its backlog is the story: $117.5m at 30 June, up 39%, and roughly $130m by early August, driven by the US Army's next-generation command-and-control program through prime contractor L3Harris. Half the 500-basis-point gross margin gain came from a one-time $1.1m tariff refund. Nothing in that is power architecture.

Vicor grew; the shares did not

Vicor's headline revenue of $143.4m looks flat, up 1.6%, but the year-ago quarter contained a $45m patent settlement. Strip it and the core product-and-royalty line grew 49.3%. Backlog rose 26% sequentially to $379.7m and 145% from a year earlier. Management raised its long-term target to $2.5bn of revenue at a 70% gross margin, from $1bn and 65%. Gross margin reached 58.0%.

The shares fell 9.8% over the month and 14.2% over three months, and sit 38.2% below their high of the past quarter. Price-to-gross-profit has compressed from 61.8x in mid-May to 39.6x trailing and 31.2x forward, while market value fell from $14.4bn to $10.6bn. That is the clearest gap in the group between a business and its price — with the qualifier that royalties reached $30.4m, a fifth of core revenue, and 68.3x forward earnings is not cheap in absolute terms.

Navitas runs the other way. Revenue fell 27.3% to $10.53m, the fourth consecutive year-on-year decline; gross margin was negative at -9.5%; the net loss was $228.2m. It debuted an 800V-to-6V power board at NVIDIA's GTC 2026, but STMicroelectronics and Texas Instruments announced supporting parts at the same show — the socket is contested. Wolfspeed sued Navitas on 7 July over five patents covering its entire product range, and Renesas followed with a trade-secret suit on 22 July. Navitas raised $373m in the quarter at $21.89 a share, about 51% above the mid-August price of $14.45.

Ideal Power booked $5,800 of revenue against a $3.62m operating loss, on an $85.9m market value of which roughly half is cash. Its prototype solid-state circuit breaker for an unnamed hyperscaler is due at the end of the fourth quarter.

The month was three sessions

The group is up about 9.5% on an equal-weight basis over 30 days, but it is down 3.2% over 90, and the July collapse was severe — Bel Fuse's two share classes each fell more than 16% on 2 July, Navitas 21.0% on 28 July. Remove each name's two best single sessions and the month becomes roughly -10.6%. Three shared rebound days did the work, and they line up with a macro reset: chip stocks shed more than $1 trillion in the July selloff, then Bank of America lifted its hyperscaler capital-spending expectation above $1.2 trillion for the coming year.

Valuations sit in four places. Bel Fuse trades at 30.5x forward earnings for the B shares and 25.9x for the A, against 72.5x trailing, and 11.0x forward gross profit — roughly a third of Vicor's multiple, on lower margins. Ultralife is at 8.7x forward earnings and 0.94x book. Navitas is at 80x forward sales with no positive gross profit; Ideal Power at 107x forward sales on $800k of consensus 2026 revenue.

The setup

Where it stands — The group's growth today comes from defense and legacy industrial demand, while the 800-volt data-center revenue it is named for begins in 2027.

Would confirm — Navitas hitting its $13.5m third-quarter guide with gross margin turning positive, and Vicor's backlog rising again from $379.7m.

Would invalidate — Bel Fuse defense growth slowing below its data-center line, or Vicor's book-to-bill dropping under 1.0.

Watch next — Third-quarter results across the six in late October and early November 2026; Ideal Power's hyperscaler breaker prototype due by 31 December.

Valuation — Vicor at 39.6x trailing and 31.2x forward gross profit, against 61.8x trailing in May; Bel Fuse at 11.9x and 11.0x.