NVIDIA P4261 — Grace Hopper carrier with no BMC and no SCM slot. Anyone recognize this board?

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er0080

New Member
Sep 2, 2026
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A batch of NVIDIA engineering boards has surfaced through liquidation and
I've been trying to work out what I'd be buying before I commit to one.
Posting what I've established in case someone here has had one on a bench,
because there is genuinely zero public documentation on it.

**The board:** `

694-24261-0000`, model P4261, silkscreened NVIDIA
Corporation Santa Clara, Made in USA. PCB `180-14261-DAAF-A00` on the units
I've seen photos of, `-A01` on another. Two long high-density mezzanine
connectors that take a GH200 superchip module. No coin cell, no BMC, and no
slot for one.

**What I've worked out:**

The matched module is `699-2G530-0215-DV5` (`Model: PG530`), and NVIDIA's
own MGX firmware docs put SKU `0215` on the 54V branch and `0206` on 12V —
so this is a 54V board. Worth noting the maturity suffixes don't track: a
`DV5` module pairs with an `EV1`-labelled board, per the seller who has
both.

The missing BMC looks architectural rather than a stripped part. OCP's
DC-SCM spec defines a Host Processor Module as the CPU-memory complex with
BMC and security moved to a separate module, which is exactly what this
is. The small finned heatsink mid-board is, I think, the HPM FPGA.

**Related equipment**

A related dual-module board turned up, and that one is fully identified
from its own service label: `P4486`, `699-24486-0000-200 D2`. Same `DAAF`
PCB family as the P4261. On the P4486 the management link is visibly
cabled — shielded bundles labelled `HMC J21` and `HMC J22` running to a
small daughtercard riser at the board edge.

The P4261 has no such riser slot anywhere on it. So either it carries the
same `HMC Jnn` connectors and the card lives elsewhere in the chassis, or
it does something different entirely.

I've also seen inside a `P4351 DGX Starship Node Chassis`
(`675-24351-2000-EVT`), which carries both a SYS MAC and a BMC MAC on its
label. Inside is a board stack, and one board carries an ASPEED AST2600
plus a coin cell, mating to the board above through a large board-to-board
card-edge connector.

**What I can't work out:**

1. Does anyone recognise P4261 specifically? It appears nowhere in NVIDIA's
docs — nvfwupd's platform list has P4351, P4352, P3809, P4764 and P4975,
but not this.
2. **Does the P4261 carry its own `HMC Jnn` connectors, and if so which
ones?** It has ~8 MCIO along the top and right edges, two large
front-edge power connectors, an ATX-style Molex and a 2x5 header. If
anyone has one in front of them, the J-numbers next to those connectors
would answer it.
3. **Is the host UEFI on the carrier or on the management card?** DC-SCM
allows either, and it decides whether the board is usable at all. If
anyone has dumped SPI flash on a Grace-generation carrier and found an
EDK2 firmware volume, I'd like to know — including a negative result.
4. Has anyone seen an NVIDIA management daughtercard from this generation
sold separately?
5. Can anyone confirm what's under the finned heatsink? I'd guess Cyclone
10 GX, on the strength of it appearing on Supermicro's G1SMH and on
NVIDIA's "Starship MB", but that's a guess.
6. I've seen the same `694-24261-0000` carrying two different suffixes on
the service label — `H1` on some units, `K1` on others. Anyone know
what differs between the spins?

Happy to be told this is a dead end — a negative answer on point 3 saves me
a four-figure mistake. If it isn't, I'll write up the whole bring-up,
because as far as I can tell nobody has ever published one for this board.
 

er0080

New Member
Sep 2, 2026
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I don't understand why people have their Claude/Codex post on forums for them. Why even bother? At least have the manners to tell your agent not to literally post Markdown...
Being a first post, I saw the markdown feature while authoring, so I copy-pasted from a markdown file my agent revised for me.

You’re right that the formatting was wrong due to my human laziness.

But the underlying context is roughly my own, and I would still appreciate any insight from members experienced with this hardware.

Eric
 

dollop

New Member
Oct 2, 2026
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I saw a few of these sold in the past few weeks, was that you Eric? :D

I've also wondered how powering up one of the p4261s would go since I've seen no record of someone running one either. Seeing this ebay posting of someone reselling one they bought makes me think it isn't trivial but I wonder how far you'd get and what the main sticking points are.

They said they didn't have a way to test which I can totally understand saying myself if I bought one and couldn't get it working but since it seems like there are many steps involved like selecting the right power supply voltage, building the correct power harness, figuring out a way to interact with the firmware as it runs so you can see how the bring up goes, it seems like there are innumerable ways that can go sideways.
 

apprisco

New Member
May 31, 2023
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Hell of a rabbit hole I'm going down here.

The P4261 is interesting. I've found a potential PCIEx16 card to drive one of the HMCs I have lying around, but overall it seems impossible to figure out how to connect them to the P4261. No way it's a MCIO to PCIE since the pcie link only trains once the GH200 boots, but something has to tell it to boot. If you figured out how to power the boards using the super weird backplane connectors, it might be possible to read the UART off of it to see where it needs to connect.
@er0080
 

dollop

New Member
Oct 2, 2026
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Oh wow so you got a p4261 that you've been playing around with already or is this virtual so far? I wasn't able to figure out what kind of HMC this board needs- I see plenty of HMC HGXs for H200s kicking around but I haven't even seen a photo of what it looks like for the GH200 line. It doesn't even look like the supermicro gh200 line has HMCs at all for example. I hoped a UART would help on the debugging side of things too.
 

apprisco

New Member
May 31, 2023
16
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3
I have ONE HGX HMC, I'm thinking of reading the firmware from it if I can to make sure i back it up, then replicating it and flashing non GH200 HMC to it.
I think I'm getting one P4261 soon to actually play around though, since Ihave the HMC I might as well.