Gigabyte AI TOP ATOM Cluster Cable: 0.5m QSFP112 400G DAC
To cluster two Gigabyte AI TOP ATOM desktop AI supercomputers you need one 0.5m QSFP112 400G passive DAC cable in the QSFP112 port on each unit. The AI TOP ATOM is Gigabyte's build of NVIDIA's GB10 Grace Blackwell platform, tuned for local model training and fine-tuning, and it carries the same ConnectX-7 NIC as the DGX Spark, so it takes the exact cable NVIDIA approves in its Spark Stacking documentation (Amphenol NJAAKK0006 / Luxshare LMTQF022-SD-R spec). Petronella Technology Group, Inc. sells it at $159 with free US shipping, in stock, shipping in 1 to 3 business days. As of August 2026, retail listings for the same NVIDIA-approved spec run $176 to $285, NVIDIA's own marketplace lists it at $99.99 but is chronically out of stock, and Amphenol's factory-direct store shows its whole QSFP112 line on backorder.
Gigabyte builds the AI TOP ATOM around its AI TOP ecosystem, aimed at engineers who want to train and fine-tune models locally rather than rent cloud GPUs. It runs the GB10 superchip with 128 GB of unified LPDDR5x memory, and the way you push past a single node's memory ceiling is to cable two or three ATOM units together. That interconnect is one specific part Gigabyte does not include, and it is the piece the distribution channel keeps running short on. The AI TOP ATOM exposes NVIDIA's GB10 clustering over two QSFP112 ports on the onboard ConnectX-7 NIC.
| Cable | 0.5m QSFP112 400G passive direct-attach copper (DAC) |
| Approved spec | Amphenol NJAAKK0006 / Luxshare LMTQF022-SD-R (NVIDIA Spark Stacking docs) |
| Fits | Both QSFP112 ports on the Gigabyte AI TOP ATOM ConnectX-7 NIC |
| Platform | NVIDIA GB10 Grace Blackwell, 128 GB LPDDR5x unified memory |
| For two ATOM units | One cable |
| For a three-node ring | Three cables (switchless, each box uses both ports) |
| Price | $159, free US shipping (in stock, ships in 1 to 3 business days) |
Clustering Gigabyte AI TOP ATOM units: how many cables and when you need a switch
Each AI TOP ATOM has two QSFP112 ports, so it follows the NVIDIA-documented GB10 topology: two units link directly with one cable, and three units form a switchless ring with three cables, each box using both ports for full pairwise connectivity. Three nodes is the switchless ceiling; with only two ports per unit, four or more ATOM units need a 200G-class QSFP switch. Clustering pools memory so a model too large for one 128 GB node runs across two or three boxes, which is exactly the headroom local fine-tuning workloads run out of first. It is a capacity play, not a raw speed boost, since each link runs around 25 GB/s. Because every GB10 system shares the ConnectX-7 NIC and QSFP112 spec, an AI TOP ATOM also clusters with a DGX Spark or any other OEM box over the same cable.