40G QSFP+ Direct Attach Copper Cable (DAC): High-Speed Intra-Rack Interconnect
The 40G QSFP+ Direct Attach Copper Cable (DAC) is a high-performance passive Twinax cable designed for short-distance 40G Ethernet links (up to 7m). It features two QSFP+ connectors directly soldered to a shielded copper cable, offering a zero-power consumption and near-zero latency solution for Top-of-Rack (ToR) switch-to-server or switch-to-switch connections. It is the most cost-effective alternative to optical transceivers for data center cabling.
DAC Cable Using in Intra-Rack and Inter-Rack Connectivity
The direct attach copper cable is commonly using in the short distance of data transmission, so the length of the DAC cable are usually 1m/2m/3m/5m/7m. For the short distance, 40G DAC cable is widely used for establishing connections within the same rack or between adjacent racks in data centers. This intra-rack and inter-rack connectivity is essential for linking networking equipment, servers, and storage devices, creating a cohesive and high-performance infrastructure within the data center environment.

Cost-effective networking solutions from DAC cable
DAC cable is to provide cost-effective networking solutions for short distance connections. As an alternative to optical transceivers and fiber optic cabling, direct attach copper cable offer comparable performance at a lower cost, making them an economical choice for high-speed data transmission in limited network space. The internal material of the high-speed DAC cables is copper core, which is both energy efficient and environmentally friendly as it provides natural heat dissipation. The active optic cables typically consume around 440mW, but the direct attached copper cable do not require a power source, it could save on the on electricity costs.

Rigorous Testing Guarantees of DAC Cable
If you are looking for a potential DAC cable solution to solve network latency, utility costs or density issues, let UnitekFiber help. We are committed to providing high-quality DAC cable that undergo stringent testing procedures. Our meticulous approach encompasses every step, from careful material selection to rigorous performance evaluations. By adhering to these rigorous standards, our DAC cable are designed to deliver reliable and high-performance data transmission in even the most demanding network environments. With the incorporation of top-quality components and our unwavering commitment to stringent testing processes, the DAC cable has become the trusted choice for network professionals who seek unparalleled quality and performance.
Technical Specifications & Comparison
In 40G networking, DAC is the undisputed king of cost-efficiency for distances under 5 meters.
| Feature | 40G QSFP+ Passive DAC | 40G QSFP+ AOC (Optical) |
| Transmission Media | Twinax Copper (30AWG-26AWG) | Multimode Fiber (OM3) |
| Max Reach | 7 Meters | Up to 100 Meters |
| Power Consumption | 0.1W (Negligible) | ~1.5W per end |
| Latency | Lowest (No O-E Conversion) | Micro-delays due to conversion |
| Cost | $ (Most Economical) | $$$ (Higher Investment) |
| Standard Compliance | SFF-8436 / IEEE 802.3ba | SFF-8436 |
Expert Insight: The UnitekFiber Advantage
I often advise clients: if your link is under 3 meters, there is absolutely no reason to pay for optics. Our 40G DACs are programmed with industry-standard EEPROM signatures, meaning they ‘handshake’ instantly with Cisco Nexus or Arista switches. No ‘unsupported transceiver’ warnings—just instant 40G throughput. — Op2Link
QSFP+ Direct Attach Cable Application & Solutions
The 40G QSFP+ DAC is the “hidden hero” of Storage Area Networks (SAN) and HCI (Hyper-Converged Infrastructure). It is perfectly suited for high-throughput backup tasks and low-latency database clustering within the same or adjacent racks.
Discover our Data Center Infrastructure Solutions to learn how to balance DAC and AOC in your network.
Optimize Your Rack Budget
Stop overspending on short-range optics. Op2Link offers premium, factory-tested 40G DACs in lengths of 0.5m to 7m. High-volume stock is available for immediate global deployment.





