NVIDIA XDR InfiniBand Cables and Optics: What 800G Actually Means
"800G" is not one thing in NVIDIA networking. There are two generations of 800G, and their cables are not interchangeable. NDR-era 800G, on Quantum-2 and Spectrum-4 switches, is a twin-port OSFP that carries two 400G links over lanes of roughly 100G. XDR is a newer 800 Gb/s InfiniBand port built on 200G-PAM4 lanes, found on Quantum-X800 switches and ConnectX-8 adapters. A cable made for the first will not give you the second. This page sorts out which is which, what NVIDIA says about copper and optics at XDR speeds, and what Resilient Tec stocks today.
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NDR "800G" vs XDR 800G
| NDR-era 800G (twin-port) | XDR 800G | |
|---|---|---|
| What an "800G" port is | Twin-port OSFP: two 400G links in one cage | One 800 Gb/s InfiniBand port |
| Signaling | About 100G per lane, 8 lanes per twin-port module | 200G-PAM4 per lane, 4 lanes per 800G port |
| Switches | Quantum-2 (QM9700, QM9790), Spectrum-4 | Quantum-X800 (Q3200-RA: 36 OSFP cages, 72 ports; Q3400-RA: 72 OSFP cages, 144 ports) |
| Adapters | ConnectX-7 (400G), BlueField-3 | ConnectX-8 (the single-port OSFP C8180 runs 800G XDR) |
| Passive copper DAC | Yes, up to about 3 m | Not offered by NVIDIA |
Switch figures come from NVIDIA's XDR switch documentation. The ConnectX-8 C8180 detail comes from third-party product guides, so confirm it against your adapter's datasheet before ordering.
Why a passive 800G DAC is not an XDR cable
At 200G per lane, copper loses signal much faster than at 100G per lane. NVIDIA's interconnect page does not offer a passive copper cable for XDR, and it describes the usable passive length at that speed as under 0.7 m. Where XDR needs copper, NVIDIA points to active copper cables, which it lists at roughly 2.5 to 3 m for 800G and 1.6T OSFP links. For anything longer, you use optics.
That is why the MCP4Y10-N001 and MCP4Y10-N002 twin-port OSFP DACs, which we sell for Quantum-2 switch-to-switch links, are NDR-generation cables. They work as designed on Quantum-2 and Spectrum-4 twin-port cages. They are not a way to cable a Quantum-X800 switch. Our full guide to the NDR side is the OSFP DAC cables guide.
What XDR links use instead
| Link type | Medium | Reach per NVIDIA | Connector |
|---|---|---|---|
| Active copper (ACC/LACC) | Copper with signal conditioning | About 2.5 to 3 m for XDR | OSFP |
| DR optics | Single-mode, 1310 nm | 500 m | MPO-12/APC |
| FR optics | Single-mode, 1310 nm | 2 km | LC duplex |
Note that the XDR optics are single-mode. The 850 nm multimode SR modules that serve NDR links over OM3 or OM4 fiber do not carry over, which means a plant built on multimode fiber needs single-mode OS2 cabling for XDR.
What we stock today
New, lifetime warranty backed by Resilient Tec, shipping from Knoxville, Tennessee. Prices checked November 11, 2026. These are NDR-generation and 800G-class parts:
- MCP4Y10-N001 — 800G twin-port OSFP DAC, 1 m, finned top — $195, Quantum-2 switch to switch
- MCP4Y10-N002 — 800G twin-port OSFP DAC, 2 m, finned top — $243.99
- MCP7Y00-N002 — 800G OSFP to 2x400G OSFP breakout DAC, 2 m — $298.45, switch to two 400G servers
- MCP7Y50-N001 — 800G OSFP to 4x200G OSFP breakout DAC, 1 m — $384
- MMA4Z00-NS compatible — 800G OSFP SR8 twin-port, finned top — $759, switch-side optic for multimode fiber
- MMA4Z00-NS400 compatible — 400G OSFP SR4, flat top — $489, server-side optic
- MPO-12/APC OS2 single-mode trunk, Type B — $55 to $121, the fiber for DR-class single-mode optics
- MPO-12/APC OM4 multimode trunk, Type B — the fiber for the SR optics above
We do not currently list XDR cables or XDR optics. If your build is Quantum-X800 or ConnectX-8, send us the part numbers and we will tell you plainly what we can source and what we cannot.
How to tell which generation you have
- Find the switch model. QM9700 or QM9790 is Quantum-2 (NDR). Q3200 or Q3400 is Quantum-X800 (XDR).
- Find the adapter. ConnectX-7 is a 400G card. ConnectX-8 is the XDR-capable card.
- Check the cage. Twin-port OSFP is the NDR switch cage; XDR uses OSFP224.
- Read the part number on the cable you already have, and check it against NVIDIA's table before you buy a replacement. Our OSFP part-number crosswalk covers the NDR range.
Frequently asked questions
Is the MCP4Y10 an XDR cable?
No. The MCP4Y10-N001 and N002 are twin-port OSFP passive DACs for NDR-generation Quantum-2 switch links. NVIDIA does not offer a passive copper cable for XDR, where usable passive reach is under 0.7 m.
What is the difference between NDR and XDR InfiniBand?
NDR is the 400G generation (about 100G per lane, or 800G as a twin-port 2x400G module). XDR is the 800 Gb/s generation built on 200G-PAM4 lanes, used on Quantum-X800 switches and ConnectX-8 adapters.
What cable do I need for XDR InfiniBand?
Active copper for runs of about 2.5 to 3 m, or single-mode optics beyond that: DR (500 m, MPO-12/APC) or FR (2 km, LC duplex). Resilient Tec does not currently list XDR cables or optics but will tell you what it can source.
Does XDR use multimode fiber?
The XDR optics NVIDIA lists, DR and FR, are single-mode. An OM3 or OM4 plant built for NDR SR optics would need single-mode OS2 cabling for XDR.
Related reading
- OSFP DAC cables guide — the NDR copper side, in depth
- 800G AI fabric buying guide — copper where you can, optics where you must
- NVIDIA OSFP part-number crosswalk
- Flat-top or finned-top OSFP?
- NVIDIA & Mellanox interconnect compatibility guide
Sources: NVIDIA XDR switch systems documentation and NVIDIA LinkX interconnect page for XDR switch models, signaling, and copper and optics reach; NADDOD XDR product guide for the ConnectX-8 adapter details.