LMTQF022-SD-R 400G QSFP112 Passive DAC Stacking Cable, 0.5m – NVIDIA DGX Spark Validated Equivalent
Warranty: Lifetime
OEM-equivalent, DGX validated
Part Number: LMTQF022-SD-R
Description: 400G QSFP112 Passive Direct Attach Copper (DAC) Stacking Cable, 0.5m (1.6 ft)
The LMTQF022-SD-R is Luxshare's 400G QSFP112 passive DAC stacking cable engineered 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. The LMTQF022-SD-R is NVIDIA's official part number for the Luxshare-manufactured version of this cable and is fully validated for DGX Spark stacking.
Use the LMTQF022-SD-R 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 | LMTQF022-SD-R |
| Manufacturer | Luxshare |
| Interface | QSFP112 |
| Data Rate | 400G (4 × 100G lanes) |
| Cable Type | Passive Direct Attach Copper (DAC) |
| Length | 0.5 m (1.6 ft) / 400mm |
| AWG | 30AWG |
| 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 |
| NVIDIA Validation | Officially validated by NVIDIA for DGX Spark |
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: LMTQF022-SD-R (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: Amphenol NJAAKK-N911 vs Luxshare LMTQF022-SD-R — What's the Difference?
Also see: NJAAKK-N911 (Amphenol version)
📋 COMPATIBILITY DOCUMENTATION
Download comprehensive compatibility report: NJAAKK-N911_Compatibility_Report
Guide includes: Pre-tested compatibility matrix for NVIDIA DGX Spark platforms, ConnectX-7 200GbE port verification, EEPROM data and recognition protocols, QSFP56 MSA compliance guidelines, dual-system interconnect setup instructions.
OEM-equivalent, DGX validated
Part Number: LMTQF022-SD-R
Description: 400G QSFP112 Passive Direct Attach Copper (DAC) Stacking Cable, 0.5m (1.6 ft)
The LMTQF022-SD-R is Luxshare's 400G QSFP112 passive DAC stacking cable engineered 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. The LMTQF022-SD-R is NVIDIA's official part number for the Luxshare-manufactured version of this cable and is fully validated for DGX Spark stacking.
Use the LMTQF022-SD-R 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 | LMTQF022-SD-R |
| Manufacturer | Luxshare |
| Interface | QSFP112 |
| Data Rate | 400G (4 × 100G lanes) |
| Cable Type | Passive Direct Attach Copper (DAC) |
| Length | 0.5 m (1.6 ft) / 400mm |
| AWG | 30AWG |
| 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 |
| NVIDIA Validation | Officially validated by NVIDIA for DGX Spark |
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: LMTQF022-SD-R (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: Amphenol NJAAKK-N911 vs Luxshare LMTQF022-SD-R — What's the Difference?
Also see: NJAAKK-N911 (Amphenol version)
📋 COMPATIBILITY DOCUMENTATION
Download comprehensive compatibility report: NJAAKK-N911_Compatibility_Report
Guide includes: Pre-tested compatibility matrix for NVIDIA DGX Spark platforms, ConnectX-7 200GbE port verification, EEPROM data and recognition protocols, QSFP56 MSA compliance guidelines, dual-system interconnect setup instructions.