An interconnect is any physical link that carries data between components in an electronic system. It can be as small as a microscopic wire connecting transistors inside a chip, or as large as a fiber-optic cable linking servers across a data center. The concept spans every scale of computing: the connections within a processor, the paths between a processor and memory, and the networks tying thousands of machines together.
How Interconnects Work Inside a Chip
A modern processor contains billions of transistors, and those transistors need to talk to each other. The tiny metal traces etched into silicon that make this communication possible are the most fundamental type of interconnect. These on-chip connections are typically made of copper and are measured in nanometers.
As chips grew more complex, simple shared pathways (called buses) couldn’t keep up. Engineers developed networks-on-chip, which work like miniature versions of the internet inside a single processor. Instead of every component sharing one lane, data gets broken into small packets and routed through a mesh of tiny on-chip routers. This approach scales far better when you’re connecting dozens of processor cores, memory blocks, and specialized processing units on a single piece of silicon.
One of the biggest recent advances is stacking chips vertically. Traditional chips are flat, so signals sometimes have to travel long distances across the surface. By stacking multiple layers of silicon and connecting them with vertical channels called through-silicon vias, engineers shorten those paths significantly. Research from Georgia Tech confirms that stacking more layers reduces the average distance signals travel, which directly improves speed and energy efficiency. The general trend: as these vertical connections shrink and more layers are added, performance gains compound.
Interconnects Between Components
Zoom out from the chip itself and you find another layer of interconnects: the links between a processor, its memory, graphics cards, storage drives, and other components on a circuit board. These are the interconnects most PC builders encounter, even if they don’t use the term.
PCIe (Peripheral Component Interconnect Express) is the dominant standard here. The latest finalized version, PCIe 6.0, transfers data at 64 gigatransfers per second per lane, delivering up to 256 gigabytes per second in a full 16-lane configuration. That’s the kind of bandwidth needed to feed modern GPUs and solid-state drives without creating a bottleneck.
A newer standard called CXL (Compute Express Link) is changing how processors interact with memory. Traditionally, memory is physically attached to a specific processor and only that processor can use it. CXL 3.1 introduces memory pooling, where multiple processors share a common pool of memory over a high-speed fabric. Each processor gets its own view of the shared address space, and switches handle the mapping between them. Data consistency is maintained through a system that invalidates outdated copies of data when something changes. This matters for servers running large workloads because it lets machines use memory more flexibly instead of leaving some idle while others run out.
Data Center and Server Interconnects
At the largest scale, interconnects link thousands of servers together. The two dominant technologies here are Ethernet and InfiniBand, and the choice between them shapes how fast a data center can operate.
Ethernet is the familiar networking standard that runs the internet. The latest specifications support speeds up to 800 gigabits per second. It’s widely compatible, well understood, and works for most general-purpose workloads. However, it wasn’t originally designed for the extreme demands of high-performance computing.
InfiniBand was built specifically for those demands. Its speeds also reach 400 to 800 Gbps with the latest NDR standard, but raw bandwidth isn’t its main advantage. InfiniBand uses a zero-packet-loss design, meaning data arrives reliably without needing to be resent. Its latency, the time it takes for a signal to travel from one point to another, is significantly lower than traditional Ethernet. For AI training and scientific simulations where thousands of processors need to exchange data in near-lockstep, those milliseconds of saved latency add up to meaningful differences in total job completion time.
Specialized Interconnects for AI
Training large AI models requires GPUs to share enormous amounts of data with each other, often faster than general-purpose network standards can handle. NVIDIA’s NVLink addresses this with a dedicated high-speed connection between GPUs. The fourth generation, used in NVIDIA’s Hopper architecture, provides 900 gigabytes per second of bandwidth per GPU. That’s several times faster than PCIe, which allows GPUs to exchange model parameters and training data without waiting on a slower link. NVLink can also connect through dedicated switches, enabling GPU-to-GPU communication across larger clusters.
Copper, Fiber, and What Comes Next
Most interconnects today use copper wiring to carry electrical signals. Copper is cheap, easy to manufacture, and works well over short distances. But it has real physical limits. Signals degrade over distance, requiring amplifiers that consume power. At higher speeds, copper generates more heat and becomes harder to shield from electromagnetic interference.
Optical (fiber) interconnects solve many of these problems. Fiber carries data as pulses of light, which travel farther without degradation. A fiber connection doesn’t need the amplifiers that copper requires over the same distance, making it inherently more energy efficient. One study found that at 50 Mbps, fiber connections produced 1.7 tons of CO2 per year compared to 2.7 tons for copper, largely because of those eliminated amplifiers. Inside data centers, optical links are already standard for longer runs between racks, and the technology is steadily moving closer to the chip itself.
The pattern across all of these scales is the same: as processors get faster and workloads get larger, the connections between components become the limiting factor. An interconnect that’s too slow or too power-hungry can bottleneck a system no matter how powerful its individual chips are. That’s why interconnect design has become one of the most active areas in computing, from nanometer-scale wires inside processors to the fiber-optic cables spanning data center floors.