Two Different Manufacturers, One NVIDIA-Approved Cable
If you're shopping for a stacking cable for your NVIDIA DGX Spark and you see two different part numbers — NJAAKK-N911 and LMTQF022-SD-R — you might wonder what's different. The short answer: they are functionally identical cables made by two different manufacturers, and both are officially validated by NVIDIA for DGX Spark stacking.
This post explains everything you need to know about each part number, who makes them, and how to choose the right one for your setup.
What These Part Numbers Are
| Attribute | NJAAKK-N911 | LMTQF022-SD-R |
|---|---|---|
| Manufacturer | Amphenol | Luxshare |
| Interface | QSFP112 | QSFP112 |
| Data Rate | 400G (4 × 100G lanes) | 400G (4 × 100G lanes) |
| Cable Type | Passive DAC (copper) | Passive DAC (copper) |
| Length | 0.5 m (400mm) | 0.5 m (400mm) |
| AWG | 32AWG | 30AWG |
| NVIDIA Validation | Yes — official DGX Spark part | Yes — official DGX Spark part |
| Use Case | DGX Spark dedicated stacking port | DGX Spark dedicated stacking port |
The Manufacturers
Amphenol — NJAAKK-N911
Amphenol is a global leader in interconnect technology and one of the original equipment manufacturers for NVIDIA DAC cables. The NJAAKK-N911 is Amphenol's part number for this specific cable. Amphenol has a long history of producing cables for NVIDIA platforms and is referenced extensively in NVIDIA's own documentation and community forums. The NJAAKK-N911 uses 32AWG wire.
Luxshare — LMTQF022-SD-R
Luxshare Precision is one of the world's largest cable and connector manufacturers, also well-known for producing Apple products and high-speed interconnects. The LMTQF022-SD-R is Luxshare's part number for the same NVIDIA DGX Spark stacking cable specification. NVIDIA lists this as an official part number in their validated cables documentation. The LMTQF022-SD-R uses 30AWG wire, making it slightly thicker than the Amphenol version.
Are They Interchangeable?
Yes — both cables perform the same function, connect the same ports, and carry the same NVIDIA validation for DGX Spark stacking. The NVIDIA Developer Forum confirms that both the Amphenol NJAAKK0006/NJAAKK-N911 and the Luxshare LMTQF022-SD-R are the only fully vetted passive DAC cables for the DGX Spark stacking port. Either cable will give you the same 400G QSFP112 passive copper stacking connection between two DGX Spark units, enabling up to 800GB/s of combined memory bandwidth.
The One Technical Difference: AWG
The only measurable technical difference between the two is the wire gauge:
- NJAAKK-N911 (Amphenol): 32AWG — slightly thinner, more flexible
- LMTQF022-SD-R (Luxshare): 30AWG — slightly thicker copper conductor
At 0.5 meters, this difference has no meaningful impact on performance or signal integrity. Both cables meet the same electrical specifications for the DGX Spark stacking port and are certified at 400G.
What Port Do These Cables Connect To?
Both cables connect exclusively to the dedicated QSFP112 stacking port on the DGX Spark — this is the single port on the back of the unit specifically for stacking two DGX Sparks together. This port is entirely separate from the two ConnectX-7 NIC ports (which use QSFP56 and are for standard 200G Ethernet networking).
Do not confuse these cables with the Q56-200G-CU0-5 QSFP56 DAC cable used for the ConnectX-7 NIC ports. The stacking port and the NIC ports are not interchangeable.
Important Limitations (Same for Both Cables)
- Only works between two DGX Spark units — cannot connect to any other NVIDIA system or third-party device
- Stacking is limited to 2 units maximum
- The 0.5m length is the only certified length per NVIDIA's DGX Spark documentation
- These cables do not add Ethernet networking capacity
Which Should You Buy?
Both are excellent choices. Choose based on availability and price. Since NVIDIA validates both from the factory, there's no technical reason to prefer one over the other for the DGX Spark stacking application. At Resilient Tec, we stock both:
Both ship same day and carry our Lifetime Warranty.