NJAAKK-N911 400G QSFP112 Passive DAC Stacking Cable, 0.5m – NVIDIA DGX Spark
Warranty: Lifetime
Part Number: NJAAKK-N911
Description: 400G QSFP112 Passive Direct Attach Copper (DAC) Stacking Cable, 0.5m (1.6 ft)
The NJAAKK-N911 is NVIDIA's proprietary 400G QSFP112 passive DAC stacking cable engineered exclusively for the NVIDIA DGX Spark's dedicated stacking port. This is not the same cable used for standard 200G Ethernet networking — it connects to a separate, purpose-built port on the DGX Spark designed specifically for high-bandwidth, low-latency GPU-to-GPU communication when stacking two Spark units together.
Use the NJAAKK-N911 when you need to stack two NVIDIA DGX Spark systems for up to 800GB/s of combined memory bandwidth. Use the Q56-200G-CU0-5 200G QSFP56 DAC for your ConnectX-7 NIC ports and standard 200G Ethernet networking.
Technical Specifications
| Specification | Value |
|---|---|
| Part Number | NJAAKK-N911 |
| Interface | QSFP112 |
| Data Rate | 400G (4 × 100G lanes) |
| Cable Type | Passive Direct Attach Copper (DAC) |
| Length | 0.5 m (1.6 ft) |
| Connector Type | QSFP112 on both ends |
| Port Compatibility | NVIDIA DGX Spark dedicated stacking port only |
| Use Case | DGX Spark 2-unit stack configuration |
| Protocol | NVIDIA proprietary stacking link |
What Port Does This Use?
The DGX Spark has two distinct port types:
- ConnectX-7 NIC ports (2×) — 200G QSFP56 — used for standard Ethernet networking. Compatible cable: Q56-200G-CU0-5
- Dedicated Stacking port (1×) — QSFP112 — used exclusively for connecting two DGX Sparks together. Compatible cable: NJAAKK-N911 (this product)
These ports are not interchangeable. The stacking port only accepts QSFP112 connectors and only communicates with NVIDIA's proprietary stacking protocol.
Important Limitations
- Only works between two DGX Spark units — cannot connect a DGX Spark to any other NVIDIA system or third-party device
- Stacking is limited to 2 units maximum — you cannot chain more than 2 Sparks
- The 0.5m length is the only supported length per NVIDIA's DGX Spark documentation — longer passive DAC cables are not certified
- Does not add Ethernet networking capacity — for networking, use the ConnectX-7 ports with the Q56-200G-CU0-5
Quick Checklist — Is This the Right Cable?
✅ You have two NVIDIA DGX Spark units
✅ You want to connect them via the dedicated stacking port
✅ Your goal is expanded unified memory (up to 800GB/s combined bandwidth)
✅ You need a 0.5m passive copper cable with QSFP112 connectors on both ends
❌ Do NOT use this cable for Ethernet networking — use the Q56-200G-CU0-5 for that
❌ Do NOT use this cable to connect a DGX Spark to any switch or non-Spark device
❌ Do NOT use this for connecting more than 2 DGX Spark units
Related Guide
Read the full technical guide: NVIDIA DGX Spark Stacking Cable NJAAKK-N911: What It Does, Who Needs It, and How It Differs from the DAC
Also see: How to Connect Two NVIDIA DGX Spark Systems: The Cable You Need and Why
Part Number: NJAAKK-N911
Description: 400G QSFP112 Passive Direct Attach Copper (DAC) Stacking Cable, 0.5m (1.6 ft)
The NJAAKK-N911 is NVIDIA's proprietary 400G QSFP112 passive DAC stacking cable engineered exclusively for the NVIDIA DGX Spark's dedicated stacking port. This is not the same cable used for standard 200G Ethernet networking — it connects to a separate, purpose-built port on the DGX Spark designed specifically for high-bandwidth, low-latency GPU-to-GPU communication when stacking two Spark units together.
Use the NJAAKK-N911 when you need to stack two NVIDIA DGX Spark systems for up to 800GB/s of combined memory bandwidth. Use the Q56-200G-CU0-5 200G QSFP56 DAC for your ConnectX-7 NIC ports and standard 200G Ethernet networking.
Technical Specifications
| Specification | Value |
|---|---|
| Part Number | NJAAKK-N911 |
| Interface | QSFP112 |
| Data Rate | 400G (4 × 100G lanes) |
| Cable Type | Passive Direct Attach Copper (DAC) |
| Length | 0.5 m (1.6 ft) |
| Connector Type | QSFP112 on both ends |
| Port Compatibility | NVIDIA DGX Spark dedicated stacking port only |
| Use Case | DGX Spark 2-unit stack configuration |
| Protocol | NVIDIA proprietary stacking link |
What Port Does This Use?
The DGX Spark has two distinct port types:
- ConnectX-7 NIC ports (2×) — 200G QSFP56 — used for standard Ethernet networking. Compatible cable: Q56-200G-CU0-5
- Dedicated Stacking port (1×) — QSFP112 — used exclusively for connecting two DGX Sparks together. Compatible cable: NJAAKK-N911 (this product)
These ports are not interchangeable. The stacking port only accepts QSFP112 connectors and only communicates with NVIDIA's proprietary stacking protocol.
Important Limitations
- Only works between two DGX Spark units — cannot connect a DGX Spark to any other NVIDIA system or third-party device
- Stacking is limited to 2 units maximum — you cannot chain more than 2 Sparks
- The 0.5m length is the only supported length per NVIDIA's DGX Spark documentation — longer passive DAC cables are not certified
- Does not add Ethernet networking capacity — for networking, use the ConnectX-7 ports with the Q56-200G-CU0-5
Quick Checklist — Is This the Right Cable?
✅ You have two NVIDIA DGX Spark units
✅ You want to connect them via the dedicated stacking port
✅ Your goal is expanded unified memory (up to 800GB/s combined bandwidth)
✅ You need a 0.5m passive copper cable with QSFP112 connectors on both ends
❌ Do NOT use this cable for Ethernet networking — use the Q56-200G-CU0-5 for that
❌ Do NOT use this cable to connect a DGX Spark to any switch or non-Spark device
❌ Do NOT use this for connecting more than 2 DGX Spark units
Related Guide
Read the full technical guide: NVIDIA DGX Spark Stacking Cable NJAAKK-N911: What It Does, Who Needs It, and How It Differs from the DAC
Also see: How to Connect Two NVIDIA DGX Spark Systems: The Cable You Need and Why