High-Speed Data Transmission Cables: DAC vs ACC vs AEC vs AOC

Choosing the Right Interconnect Solution for Your Application

Selecting the right high-speed data center cables requires balancing performance, distance, and cost considerations. DAC, ACC, AEC, and AOC cables offer integrated solutions that eliminate the need for separate transceivers and patch cables, reducing both complexity and total system costs. Each cable type is optimized for specific applications – from short rack-to-rack connections to long-distance runs between data center aisles.

DAC (Direct Attach Cable):

Direct Attach Cables are passive copper cables designed for short-distance connections. Originally developed for 10G SFP+ applications, DACs now support speeds up to 800G and 1.6TB while maintaining the lowest power consumption for short-range connectivity.

BENEFITS

  • Cost-Effective

    DAC are significantly cheaper than using a separate transceiver and fiber optic patch cable. This makes them a budget-friendly option for connections within the same rack or between adjacent racks.

  • Lowest Power Consumption

    Passive DACs consume virtually no power, as they have no active electrical components. This helps reduce energy costs and heat generation in data centers.

  • Low Latency

    Because they use direct electrical signaling over copper, DACs avoid the electrical-to-optical conversion process, resulting in extremely low latency.

  • Durability

    DACs are made of copper, which is more robust and less fragile than fiber optic glass. They can withstand more handling and are less susceptible to damage from dust or dirt, which can affect optical connections.

CONS

  • Limited Distance

    This is the biggest drawback of DAC. Due to signal degradation over copper, their reach is very limited, the higher the data rate, the lower the length achievable.

  • Bulk & Weight

    Copper cables are much thicker and heavier than fiber optic cables. In high-density environments, a large number of DACs can lead to significant cable management challenges, obstructing airflow and making racks difficult to work in.

  • EMI Susceptibility

    As copper-based cables, DACs are susceptible to electromagnetic interference (EMI) from other electrical equipment. While shielded, they may not be the best choice for environments with high electrical noise.

  • Lack of Flexibility

    The thicker, more rigid nature of DACs makes them less flexible than fiber optic cables, which can be difficult to route in tight spaces or around sharp bends.

ACC (Active Copper Cable)

Active Copper Cables are the next progression from passive DACs. The key upgrade is an integrated circuit chip that amplifies the electrical signal, extending the reach of copper connections beyond passive DAC limits.

BENEFITS

  • Intermediate Reach

    The primary advantage of an ACC is its ability to extend the transmission distance of a copper connection. In most cases this extends up to 3 meters over the passive DAC counterpart which can provide just enough distance physically required.

  • Cost Effective

    While more expensive than passive DACs, ACCs are significantly cheaper than Active Optical Cables (AOCs) and transceiver-plus-fiber solutions. They provide a high-speed, cost-effective option for short-to-medium-range connections where fiber is not required.

  • Power Efficient

    ACCs are more power-efficient than AOCs. The active chip in an ACC consumes a minimal amount of power (typically 1.5W per end) which is very efficient vs other solutions such as AOC.

  • Lower Latency

    Like passive DAC, ACCs maintain very low latency because the data remains in an electrical format, avoiding the time-consuming electrical-to-optical conversion process.

CONS

  • Limited Distance

    Although they have a longer reach than passive DACs, ACCs are still limited by the physical properties of copper and can offer only limited distance requirements.

  • Bulk & Weight

    ACCs, being copper-based, are thicker and heavier than fiber optic cables. In a high-density environment, managing a large number of these cables can be challenging and may restrict airflow within a rack.

  • EMI Susceptibility

    As copper-based cables, ACCs are susceptible to electromagnetic interference (EMI) from other electrical equipment. While shielded, they may not be the best choice for environments with high electrical noise.

  • Lack of Flexibility

    The thicker, more rigid nature of ACCs makes them less flexible than fiber optic cables, which can be difficult to route in tight spaces or around sharp bends.

AEC (Active Electrical Cable)

Active Electrical Cables are an advanced type of copper cable designed to bridge the gap between the limited reach of ACCs and the high cost of AOCs. They use sophisticated retimer chips at each end to regenerate the data signal, significantly improving signal integrity and transmission distance.

BENEFITS

  • Extended Reach

    AECs in higher data rates such as 400G/800G provide a much longer reach than passive DACs and ACCs. By regenerating the signal (not just amplifying it), they can support longer transmission, making them ideal for connections between switches in a data center or across multiple racks.

  • Superior Signal Integrity

    The retimer chip in an AEC actively cleans up noise, jitter, and signal distortion. This results in a cleaner, more reliable signal with a lower bit-error rate, which is crucial for high-performance computing and AI applications.

  • Thinner & Lighter

    AECs can use a smaller gauge of copper wire than DAC/ACC, making them thinner, lighter, and more flexible. This significantly improves cable management, airflow, and cooling in high-density rack environments.

CONS

  • Higher Cost & Power Consumption

    Compared to a passive DAC, an AEC has a higher initial cost and consumes more power due to the advanced retimer chip. This must be weighed against the benefits of extended reach and better signal quality.

  • Increased Latency

    The retiming process, while beneficial for signal integrity, introduces a small amount of latency. While this is negligible for most applications, it can be a factor in ultra-low-latency environments like high-frequency trading where every nanosecond counts.

  • Still Copper Based

    Although improved upon the limitations of copper, AECs are still susceptible to Electromagnetic Interference (EMI) to some degree. For environments with high EMI, or for very long distances, fiber optic solutions (AOCs or transceivers) are the superior choice.

AOC (Active Optical Cable)

Active Optical Cables use fiber optics to transmit data over long distances. They feature integrated optical transceivers at each end, creating a single cable assembly. This design provides cost-efficient connectivity for distances up to 100 meters, the longest reach available in fixed-length high-speed data cables.

BENEFITS

  • Long-Distance Reach

    AOCs are the best choice for long-distance connections in a data center, capable of extending up to 100 meters or more. This is a massive advantage over copper-based cables (DAC, ACC, and AEC), which are limited to very short distances due to signal degradation.

  • Immunity to EMI

    Because AOCs transmit data using light through fiber optic strands, they are completely immune to Electromagnetic Interference (EMI) and radio frequency interference (RFI). This ensures a clean, reliable signal in environments with a lot of electrical noise.

  • Lightweight & Flexible

    Fiber optic cables are significantly lighter and thinner than copper cables. This makes AOCs much easier to route and manage in high-density rack environments, improving airflow and reducing stress on equipment ports.

CONS

  • Highest Cost

    AOCs are the most expensive type of cable among the four due to the integrated optical components (lasers and photodiodes) at each end.

  • Highest Power Consumption

    The electrical-to-optical conversion process requires a significant amount of power, making AOCs the most power-hungry cable type. While they are a great option for long distances, this power consumption adds to a data center's operational costs.

  • Less Durable

    The fiber optic core of an AOC is more fragile than copper and is susceptible to damage from sharp bends or physical stress. If one of the fixed transceivers or the cable itself is damaged, the entire assembly must be replaced.

Comparison Chart – Length & Power Consumption

DAC (Passive Copper)
ACC (Active Copper)
AEC (Active Electrical)
AOC (Active Optical)
10G
Up to 10 meters, 0.1W
Up to 15 meters, 0.5W
Not commonly used
Up to 100 meters, 1W
25G
Up to 5 meters, 0.1W
Not commonly used
Not commonly used
Up to 100 meters, 1W
40G
Up to 7 meters, 0.1W
Up to 10 meters, 1.5W
Not commonly used
Up to 100 meters, 1.5W
100G
Up to 5 meters, 0.1W
Not commonly used
Not commonly used
Up to 100 meters, 2.5W
200G
Up to 3 meters, 0.1W
Up to 7 meters, 1.5W
Up to 7 meters, 4.5W
Up to 100 meters, 4.5W
400G
Up to 3 meters, 0.1W
Up to 5 meters, 1.5W
Up to 7 meters, 4.5~6W*
Up to 100 meters, 8W
800G
Up to 2 meters, 0.1W
Up to 5 meters, 1.5W
Up to 7 meters, 10W
Up to 100 meters, 12~14W*

* QSFP-DD & OSFP FORM FACTOR WILL VARY IN POWER CONSUMPTION (OSFP BEING HIGHER)