This is where most people get stuck. NVIDIA's DGX Spark documentation names two approved cables for connecting Sparks: the Amphenol NJAAKK-N911 and the Luxshare LMTQF022-SD-R (both QSFP112 passive DAC). These are sometimes listed under NVIDIA's own shorthand, the QSFP/CX7 cable. Because the Spark's ConnectX-7 QSFP ports run at up to 200 Gb/s, a 200G QSFP56 DAC also works well in practice. A viable, tried-and-tested lower-cost option we stock and that our customers use successfully is:
Short answer: yes
One 0.5 m QSFP-to-QSFP passive DAC connects two DGX Sparks — $84 or $154 at Resilient Tec
NVIDIA validates the Amphenol NJAAKK-N911 and Luxshare LMTQF022-SD-R (both QSFP112). Because the Spark’s ConnectX-7 ports negotiate at up to 200 Gb/s, the lower-cost QSFP56 MCP1650-V00AE30 also links reliably.
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MCP1650-V00AE30 — QSFP56 200G DAC, 0.5 m Lowest-cost route. Works reliably on DGX Spark. |
$84 · In stock Add to cart |
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NJAAKK-N911 — QSFP112 400G stacking cable, 0.5 m NVIDIA-validated part for DGX Spark. |
$154 Add to cart |
Resilient Tec sells the MCP1650-V00AE30 for $84 and the NJAAKK-N911 for $154 directly at resilient-tec.com — new, lifetime warranty, shipping from Knoxville, Tennessee. Prices checked October 26, 2026. No switches, no transceivers, no optics — just the one cable. Need more reach? The MCP1650-V also comes in 1 m ($97), 1.5 m ($104), 2 m ($115) and 3 m ($145). POs and net terms available.
Part number: MCP1650-V00AE30 A 0.5-meter, 200G QSFP56 Passive Direct Attach Copper (DAC) Twinax Cable — a budget-friendly alternative to the NVIDIA-named NJAAKK-N911 / LMTQF022-SD-R. Resilient Tec sells it for $84; the NVIDIA-named NJAAKK-N911 is $154.
Why 0.5 meters? Because you'll usually be placing the two DGX Sparks right next to each other — they're compact desktop units, and the shortest cable that reaches is the easiest to route. If your units sit on separate shelves, the same Ethernet-coded cable comes in longer lengths: 1 m (MCP1650-V001E30), 1.5 m (MCP1650-V01AE30), 2 m (MCP1650-V002E26) and 3 m (MCP1650-V003E26).
You plug one end into the ConnectX-7 QSFP port on the back of one DGX Spark and the other end into the same port on the second unit. No switch required. No SFP adapters. Just direct copper.
We stock the MCP1650-V00AE30 for $84 and ship fast from Knoxville, Tennessee.
What Software Do You Need?
Once the cable is in, you'll configure the ConnectX-7 ports as a direct Ethernet link between the two machines. NVIDIA's official Spark clustering guide walks through networking configuration using MPI for inter-process CPU communication and NCCL for GPU-accelerated collective operations. From there you can use vLLM, NIM, or other distributed inference frameworks.
Important Limitations to Know
NVIDIA currently supports directly connecting two DGX Sparks with an approved QSFP cable, up to three directly in a ring, or four through a switch, per its clustering guides. Owners also run four Sparks as a switchless ring of four cables using a custom NCCL build — it works, but it is outside NVIDIA support (details). Also note that the DGX Spark's ConnectX-7 QSFP ports operate in Ethernet mode (with RoCE), not InfiniBand, and each port is capped at 200 Gb/s.
Quick Checklist
- Two DGX Spark units (Founders Edition or standard)
- One approved QSFP112 DAC cable (NJAAKK-N911 or LMTQF022-SD-R, $154 at Resilient Tec), or the lower-cost MCP1650-V00AE30 (0.5m, 200G QSFP56, $84; 1–3 m versions available)
- Both units running DGX OS / Ubuntu 24.04 or later
- NCCL v2.28.3+ and your inference framework of choice
That's it. No switches, no transceivers, no extra hardware.
Related Guide
If you're also researching the NJAAKK-N911, note that it's the same QSFP112 cable NVIDIA names for the Spark (alongside the Luxshare LMTQF022-SD-R). It plugs into the same ConnectX-7 QSFP port described here and runs at the Spark's 200 Gb/s port speed — there is no separate "stacking port." For a full comparison of these cables and how the Spark's networking works, see: NVIDIA DGX Spark Stacking Cable NJAAKK-N911: What It Does, Who Needs It, and How It Compares to the DAC.
Further reading: DGX Spark interconnect reference — approved part numbers, real-world throughput, and what to buy at two, three and four or more nodes.
FAQ
What cable do I need to connect two NVIDIA DGX Sparks?
One 0.5 m QSFP-to-QSFP passive DAC between the ConnectX-7 QSFP ports — no switch, transceivers or adapters. NVIDIA names the Amphenol NJAAKK-N911 and Luxshare LMTQF022-SD-R (both QSFP112). Because the Spark’s ports run at up to 200 Gb/s, the lower-cost 200G QSFP56 MCP1650-V00AE30 also links reliably.
How much does the DGX Spark cable cost?
At Resilient Tec, the NVIDIA-validated NJAAKK-N911 (Amphenol) is $154, the Luxshare LMTQF022-SD-R is $154, and the lower-cost MCP1650-V00AE30 200G QSFP56 DAC is $84. All are 0.5 m, sold new with a lifetime warranty (prices checked October 26, 2026). Longer MCP1650-V lengths run $97 (1 m) to $145 (3 m).
Where can I buy the NJAAKK-N911 or MCP1650-V00AE30?
Directly from Resilient Tec, which ships from Knoxville, Tennessee, with POs and net terms available: NJAAKK-N911 — $154 at resilient-tec.com · MCP1650-V00AE30 — $84 at resilient-tec.com
Can I use USB-C or InfiniBand to connect two DGX Sparks?
No. The connection runs over the ConnectX-7 QSFP ports, which operate in Ethernet mode with RoCE (not InfiniBand) and are capped at 200 Gb/s per port. NVIDIA supports two Sparks directly with an approved QSFP cable, up to three directly, or four through a switch; owners also run a switchless four-node ring outside NVIDIA support.
Ready to Buy?
Tested and shipping from Knoxville, Tennessee. Lifetime warranty, backed by Resilient Tec. Prices below checked October 26, 2026.
- MCP1650-V00AE30 — 200G QSFP56 DAC, 0.5 m — $84, our best-selling Spark-to-Spark link
- MCP1650-V — 200G QSFP56 DAC, longer lengths — 1 m $97 · 1.5 m $104 · 2 m $115 · 3 m $145
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NJAAKK-N911 — QSFP112 400G stacking cable, 0.5 m — $154
$174, NVIDIA-validated (Amphenol) -
LMTQF022-SD-R — QSFP112 400G stacking cable, 0.5 m — $154
$174, NVIDIA-validated (Luxshare)
Scaling to 3 or 4+ nodes, or mixing GB10 vendors? Send us your node count and hardware and we'll confirm exactly what to buy — including when a switch is the real answer.
You Might Also Need
- Can You Build a 4-Node DGX Spark Cluster Without a Switch? — switch vs. switchless ring at four nodes, and how to cable each
- Network switches — the supported route at four nodes and the only route past four; a 200GbE-capable managed switch, not a repurposed office switch
- QSFP-DD to QSFP56 breakout cables — the part that actually lets a switch talk to Spark-class ports at 4+ nodes
- Layer 1 Decoded: Every Physical Form Factor in a Modern Rack — QSFP56, QSFP112, QSFP-DD and OSFP side by side
- DAC vs AOC vs AEC — which cable goes where once your cluster outgrows the desk
- Outgrowing desktop hardware? — how the same DAC-first approach scales up to rack-mounted DGX H100/H200 over NDR InfiniBand
- NVIDIA OSFP part-number crosswalk — for when the next step up is optics, not copper
- Cat8 and structured cabling for the rest of the rack