DGX Spark Interconnect Reference: NJAAKK-N911, NJAAKK-0006 and LMTQF022-SD-R
What the approved DGX Spark stacking cables are, what they actually deliver, and what to buy at two, three and four or more nodes.
Maintained by Resilient Tec · last verified 13 September 2026 · see also our NVIDIA DGX Spark Interconnect Compatibility Matrix
Short answer
NVIDIA names two manufacturers for the DGX Spark direct-connect cable, across two lengths. All of them are the same specification — QSFP112 passive copper — and any of them works:
- Amphenol NJAAKK-N911 — QSFP to QSFP112, 32AWG, 400 mm, LSZH.
-
Amphenol NJAAKK-0006 (also written
NJAAKK0006) — the 0.5 m version of the same cable. - Luxshare LMTQF022-SD-R — QSFP112 400G DAC, 400 mm, 30AWG.
If you have seen several of these numbers and wondered which you need: you need one cable. The part numbers differ by manufacturer and by length, not by quality or capability. Length is the only thing that actually separates them — see the decoder below.
Identification
| Amphenol part number |
NJAAKK-N911 (400 mm) · NJAAKK-0006 / NJAAKK0006 / SF-NJAAKK0006-000.5M (0.5 m) |
| Luxshare part number |
LMTQF022-SD-R (400 mm) |
| Compatible-market numbers |
NJAAKKR-0006 and similar variants — compatible builds rather than OEM parts. See the decoder. |
| Also sold as | PNY DGX Spark Stacking Cable · "NVIDIA DGX Spark Connect Cable" · "Spark stacking / cluster cable" · DGX Spark Founders Edition kit 940-54242-0000-000
|
| Connector | QSFP112, both ends |
| Cable type | Passive direct attach copper (DAC). No transceivers, no power, no firmware. |
| Rated | 400G (4 × 100G lanes) |
| Delivered on DGX Spark | Up to 200 Gb/s per port — see throughput |
| Conductor gauge | 32AWG (Amphenol) · 30AWG (Luxshare) |
| Jacket | LSZH (Amphenol) |
| Host port | ConnectX-7, QSFP, on GB10-based systems |
| Port mode | Ethernet only. The QSFP ports do not run native InfiniBand. |
Part number decoder
This is the single most common point of confusion on this cable, and it costs people returns. Several numbers circulate, they are not interchangeable, and the thing that separates them is length.
| Part number | Length | Source | What it is |
|---|---|---|---|
NJAAKK-N911
|
400 mm (1.3 ft) | Amphenol | NVIDIA-listed approved cable — the short version |
NJAAKK-0006 · NJAAKK0006 · SF-NJAAKK0006-000.5M
|
0.5 m (1.6 ft) | Amphenol | NVIDIA-listed approved cable — the 0.5 m version |
LMTQF022-SD-R
|
400 mm (1.3 ft) | Luxshare | NVIDIA-listed approved cable — Luxshare equivalent |
NJAAKKR-0006
|
0.5 m (1.6 ft) | compatible market | A compatible-market spelling of the 0.5 m part |
Compatible builds vs OEM parts
Alongside the genuine Amphenol and Luxshare parts, the market carries compatible QSFP112 passive DACs — often under lightly modified spellings of the same numbers. From a reputable source these meet the same electrical specification and work normally in DGX Spark and GB10 systems, but they are not the OEM part, and any vendor blurring that line is one to avoid.
What Resilient Tec stocks: a compatible NJAAKK-N911 build at 0.5 m, matching the specification of the Amphenol NJAAKK-0006. See the listing. If you need a genuine OEM part number for procurement reasons, ask us to source it rather than substitute.
Note also that compatible suppliers frequently apply the N911 family number to a 0.5 m cable, even though Amphenol's own N911 is the 400 mm part. Always buy on stated length, not on the part number alone.
Compatibility
Any GB10-based system exposing the ConnectX-7 QSFP ports takes the same cable. The DGX Spark design is licensed to several OEMs, and the interconnect does not change between them.
| System | Ports | Cable |
|---|---|---|
| NVIDIA DGX Spark | 2 × QSFP (ConnectX-7) | Yes |
| ASUS Ascent GX10 | 2 × QSFP (ConnectX-7) | Yes |
| Dell Pro Max with GB10 | 2 × QSFP (ConnectX-7) | Yes |
| HP ZGX Nano AI Station | 2 × QSFP (ConnectX-7) | Yes |
| Standard QSFP-DD switch port | QSFP-DD | No — QSFP-DD cages are physically deeper; you need an adapter or breakout cable |
Throughput: what you actually get
The cable is rated 400G. A DGX Spark port tops out at 200 Gb/s. NVIDIA's own guidance is simply to use cables known to deliver at least 200 Gb/s — a faster cable buys you nothing here.
The more useful detail, which is not obvious from any spec sheet: GB10 connects to the ConnectX-7 over two PCIe Gen5 x4 links rather than one wider link, because the GB10 silicon cannot present a wider-than-x4 interface per device. Each x4 link is roughly 100 Gbps, and the NIC runs in multi-host mode to aggregate them. The operating system sees four network interfaces behind two physical ports.
Plan for it as 2 × 100G, not 2 × 200G. Independent testing with RoCE and parallel streams measured 185–190 Gbps in practice. Bind your interfaces carelessly and the same hardware delivers 80–100 Gbps — not a cable fault, and no cable will fix it.
What to buy, by cluster size
Two nodes. One cable, port 0 on each unit. This is the case the approved cable list exists for. Buy one NJAAKK-N911, NJAAKK-0006 or LMTQF022-SD-R and you are done.
Three nodes. Three cables in a ring, using both QSFP ports on every unit. Still no switch. This is the configuration most people do not realise is supported, and it is the last one that is.
Four or more nodes. A managed switch becomes mandatory, and this cable stops being the answer. Switch ports are QSFP-DD, which is physically deeper than the QSFP112 cage on the Spark, so you need either QSFP-DD to QSFP56 adapter cables or QSFP-DD to dual-QSFP56 breakout cables. Breakouts are the better buy: two of them fill four switch ports and serve up to eight nodes.
The mistake that costs 75% of your bandwidth
After cabling a switch, set each connected port to 200 Gbps manually. Left on auto-negotiate, these links commonly settle at 50 Gbps. The cluster works, nothing errors, and you quietly lose three quarters of your fabric. Check it before you benchmark anything.
Selection summary
| Nodes | Switch | What you need |
|---|---|---|
| 2 | No | 1 × NJAAKK-N911 (400 mm), NJAAKK-0006 (0.5 m) or LMTQF022-SD-R (400 mm) |
| 3 | No | 3 × the same cable, ring topology |
| 4–8 | Yes | 400G managed switch + 2 × QSFP-DD to 2 × QSFP56 breakout DAC, ports pinned to 200G |
Sources
- Approved cable list, part numbers, both Amphenol lengths and Ethernet-only port mode — NVIDIA DGX Spark User Guide, ConnectX-7 Networking
- Dual PCIe Gen5 x4 topology, multi-host mode, 185–190 Gbps measured — ServeTheHome, GB10 ConnectX-7 200GbE analysis
- Three-node ring limit, switch requirement at four nodes, breakout cabling, auto-negotiate warning — Exxact, building a 4× DGX Spark cluster
- Multi-node cluster configuration — NVIDIA Sync Cluster Assistant