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A network interface card (NIC) is hardware that lets a computer or server send and receive network traffic. In a data center, a NIC is part of the host-to-network system: choosing one means checking its server connection, network protocol, ports, link speed, cabling or optics, software support, and power and cooling needs—not just its speed label.
What is a network interface card?
NIST’s glossary, attributing its definition to NIST SP 800-82 Rev. 2, defines a network interface card as “A circuit board or card that is installed in a computer so that it can be connected to a network.” That definition describes a card, but current technical usage is broader: “NIC” can also mean an integrated network controller or another kind of network adapter. It does not always refer to a removable board. NIST CSRC’s glossary entry records the term.
In practical terms, the NIC provides the host-side network interface. Depending on the implementation, it connects through a wired physical link or a wireless radio. This data-center glossary focuses on wired server adapters, which commonly connect a server to a switch and handle network input and output with support from the system’s driver.
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A NIC connects a server’s network stack to a supported network so the host can transmit and receive traffic. The particular adapter may also support capabilities such as hardware traffic offloads, virtualization features, or Remote Direct Memory Access (RDMA). These are model- and configuration-dependent, not features of every NIC. For example, NVIDIA’s ConnectX-4 manual describes RDMA/RoCE use, while Broadcom’s PCIe NIC specification sheet lists features including SR-IOV, RoCE, and packet-processing offloads for specified adapters.
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- 2.5 Gbps PCIe Network Card: With the 2.5G Base-T Technology, TX201 delivers high-speeds of up to 2.5 Gbps, which is 2.5x faster than typical Gigabit adapters. Performance varies by conditions, distance to devices, and obstacles such as walls
- Versatile Compatibility – The Ethernet Network Adapter is backwards compatible with multiple data rates(2.5 Gbps, 1 Gbps, 100 Mbps Base-T connectivity). The 2.5G Ethernet port automatically negotiates between higher and lower speed connection.
- QoS: Quality of Service technology delivers prioritized performance for gamers and ensures to avoid network congestion for PC gaming
- Wake on LAN – Remotely power on or off your computer with WOL, helps to manage your devices more easily
- Low-Profile and Full-Height Brackets: In addition to the standard bracket, a low-profile bracket is provided for mini tower computer cases
NICs are used for different kinds of host connectivity, including application traffic, storage traffic, virtualization, and management. A consumer desktop Ethernet card, a high-speed server Ethernet adapter, an InfiniBand host-channel adapter, and a data-processing unit (DPU) can serve different roles; the label alone does not establish which functions a particular product supports.
How does a network interface card work?
The host connects to the NIC through an internal interface, and the NIC exposes one or more network-facing ports or another supported link. The driver and firmware allow the operating system and adapter to communicate. Network traffic then travels over a compatible medium to a switch or other peer. The exact division of work between host software and adapter hardware depends on the product and enabled features.
Keep the two sides distinct when checking compatibility: a server NIC might use PCI Express inside the host and Ethernet over a QSFP-family port toward the switch. PCIe generation and lane width describe the host connection; Ethernet link rate describes a network connection. One does not imply the other.
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- Ultra-Fast: 10/100/1000Mbps PCIe Adapter upgrade your Ethernet speed to Gigabit
- Automation: Wake-on-LAN supporting Auto-Negotiation and Auto MDI/MDIX
- Supports: IEEE802.3x Flow Control for Full-duplex Mode and backpressure for Half-duplex Mode; 4k Bytes Port: 1x 10/100/1000Mbps RJ45 Network Media
- Compatibility: Windows 11, 10, 8.1, 8, 7, Vista, XP
- Dual Bracket: Low profile and standard profile bracket inside works with both mini and standard size PCs.
What types of NICs are used in servers?
Integrated controllers and add-in cards
A network controller may be integrated onto a motherboard, or connectivity may come from a separate adapter. A discrete server NIC can be a standard PCIe stand-up card or a module using a server-specific form factor such as OCP Spec 3.0. The Open Compute Project’s Server/NIC project describes work on open, disaggregated NIC solutions and hardware and firmware interface specifications intended to support interoperability. OCP is an ecosystem and specification effort, not a synonym for every NIC.
Server-specific examples illustrate the variety: NVIDIA’s ConnectX-4 manual covers PCIe Gen 3 cards with x8 or x16 edge connectors and QSFP28 options; its ConnectX-7 manual covers PCIe stand-up and OCP Spec 3.0 forms.
Ethernet and InfiniBand adapters
Ethernet and InfiniBand are distinct network protocols. Some product families offer variants for either protocol, but the selected adapter and its configuration must match the network equipment and software environment. Do not assume that an Ethernet NIC can communicate using InfiniBand. For any model, check the exact supported protocol and configuration rather than relying on the family name.
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- 10 Gbps PCIe Network Card: With the latest 10GBase-T Technology, TX401 delivers extreme speeds of up to 10 Gbps, which is 10× faster than typical Gigabit adapters, guaranteeing smooth data transmissions for both internet access and local data transmissions[1]
- Versatile Compatibility: With extreme speed and ultra-low latency, 10GBase-T is backwards compatible with multiple data rates (10 Gbps, 5 Gbps, 2.5 Gbps, 1 Gbps, 100 Mbps), automatically negotiating between higher and lower speed connections
- QoS: Quality of Service technology delivers prioritized performance for gamers and ensures to avoid network congestion for PC gaming
- Free CAT6A Ethernet Cable: To maximize TX401's performance, a 1.5 m CAT6A Ethernet Cable is included—rated for up to 10 Gbps while a regular cable is only rated for 1 Gbps
- Low-Profile and Full-Height Brackets: In addition to the standard bracket, a low-profile bracket is provided for mini tower computer cases
SmartNICs and DPUs
“SmartNIC,” “SuperNIC,” and “DPU” are product-category or vendor terms whose boundaries vary. They should not be treated as exact synonyms for a basic NIC. Compare the documented functions—such as traffic offload, programmability, or data processing—on the specific product in question.
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Link speed is a capability, not a throughput guarantee
NICs are commonly described using bit rates such as 1, 10, 25, 50, 100, or 400 Gb/s. Those figures describe supported link capabilities for a model and mode; they do not promise end-to-end application throughput. The negotiated link and actual results depend on the NIC, switch or peer, transceiver or cable, configured mode, host, and workload. A link cannot operate beyond what its compatible components and configuration support.
Keep specifications tied to their products. NVIDIA’s undated ConnectX-4 user manual lists adapter options supporting 1/10/25/40/50GbE; Broadcom’s undated brief specifies a particular single-port BCM957414A4140C adapter at 40/50 Gb/s over PCIe 3.0 x8. AMD’s AI NIC Pollara 400 operations guide, revision 1.8 released 2026-09-08, documents a 400 Gbps Ethernet adapter. These are vendor-published specifications, not general performance benchmarks for NICs.
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- ⭐【Super-fast 2.5Gbps Networking】High up to 2.5x-speed with Realtek RTL8125B chip, much faster data-transfer speeds for gaming, living broadcasts and downloads in bandwidth-demanding tasks.
- ⭐【Complete Compatibility】Seamless backward compatibility for 2.5Gbps/1Gbps/100Mbps, Support Windows11/10/8.1/8/7, MAC OS and Linux, no dirver needed on Windows10, easily download the driver in Realtek official website for other OS.
- ⭐【PCIe to 2.5G RJ45】 This 2.5GBASE-T PCIe Network Adater convers a PCIe slot(X1/X4/X8/16) into a 2.5G RJ45 Ethernet Port. Note: Only work with PCIe slot, not for PCI slot.
- ⭐【Widely Use with Heat Sink】Comes with standard bracket and low-profile-bracket to meet the needs of different cases such as desktop, workstation, server, mini tower computer and so on. Excellent heat dissipation can reduce the temperature quickly and maintain the stability of network transmission.
- ⭐【Customer Service】Each GigaPlus 2.5G NIC has been rigorously tested for reliability, quality, and performance. We provide lifetime technical support for the entire product.
Connector shape alone does not reveal the supported speed or link mode. NVIDIA’s undated Data Center Layer 1 Cheat Sheet illustrates Ethernet configurations using SFP+, SFP28, QSFP28, and QSFP56 form factors, with examples spanning 1/10/25/40/50/100GbE NRZ and 200/400/800GbE PAM4. These configurations are not interchangeable merely because a port or cable looks similar.
Port count and media
Port count determines how many network links the adapter can provide, but port type and media matter too. Network-facing options can include RJ45 copper, a supported pluggable transceiver, or a direct-attach cable (DAC). As a model-specific example, Broadcom’s BCM957414A4140C brief describes a 40/50 Gb/s, single-port PCIe 3.0 x8 Ethernet NIC supporting QSFP28/QSFP+ optical transceivers or copper DAC. That is not a rule for all NICs.
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- Supports Windows 7/8/2000/XP/Vista/Windows Server 2003/2008/2012; Novell Netware 5.x/6.x; Linux; FreeBSD 7.x or later; DOS; SCO Open Server; UnixWare / OpenUnix 8; Sun Solaris x86; OS Independent Vmware ESX (Does not support VMware ESXi 7.0 or above)
- PCI Express 2.1. 2.5 GT/s x1 Lane. Compatible with x1, x2,x4, x8, x16 standard and low-profile PCI Express slots.
- Compatible with IPMI pass-through (SMBus or NC-SI), iSCSI boot, WoL, PXE remote boot, VLAN filtering
- Support Network Management Protocol (SNMP) and Remote Network Monitoring (RMON).
- Imported alloy heat sink , can effectively remove excess heat , keep the network card at normal operating temperature and double stable operation
How to compare NICs for a server
Use the server, network, and workload as a compatibility chain. A card that fits physically may still lack the right protocol, media, driver, power budget, or airflow. Check these items for the exact adapter and system:
- Host support: Confirm an available PCIe slot with the required generation and lane width, or verify the server supports the adapter’s OCP form factor. Check bracket type, card length, clearance, and any system-specific compatibility requirements.
- Power and cooling: Verify slot power delivery, thermal design, and airflow. NVIDIA’s ConnectX-7 manual explicitly cautions users to provide required slot power and airflow; follow the requirements for the particular server and card.
- Protocol and software: Confirm Ethernet, InfiniBand, or the exact supported combination; check operating-system driver and firmware availability for the intended server and configuration.
- Link requirements: Compare the required speed, number of ports, switch compatibility, and—where relevant—autonegotiation and forward error correction (FEC) modes. Verify that required RDMA/RoCE, SR-IOV, or other offloads are supported by the exact model and software stack.
- Cabling and optics: Identify whether the link needs RJ45 copper, a specific pluggable transceiver, or a DAC. Check form factor, medium, reach, and compatibility at both ends; a cable or optic that fits is not necessarily supported for the intended speed or link.
- Operational role: Account for whether the adapter will carry application, storage, virtualization, or management traffic, and check support lifecycle requirements for the environment.
Compare candidate adapters across link mode and throughput capability, port number and type, host compatibility, media availability and cost, required protocol and offloads, and power and airflow. There is no universal “best NIC” independent of those requirements.
Is a NIC the same as an Ethernet card?
People often use “network card” and “Ethernet card” interchangeably when they mean a wired Ethernet adapter. NIC is broader: it can refer to an integrated controller, a wireless adapter, or hardware for another network protocol. An Ethernet card is one kind of network interface implementation, not a definition of every NIC.
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Does every NIC need a PCIe slot?
No. A NIC may be integrated into the motherboard or use another supported form factor, including a server OCP module. PCIe stand-up cards are one common server implementation, not a requirement for network connectivity.
What does a higher-speed NIC change?
A higher-rated NIC can provide a faster link when the adapter, host, switch or peer, media, and configuration all support that rate. It does not by itself make every part of a network or application faster; performance depends on the whole path and workload.
How are SmartNICs and DPUs different from basic NICs?
There is no universal boundary conveyed by those labels. Read the product documentation for the specific offload, programmability, virtualization, or data-processing functions, then verify that the required drivers, firmware, host, and network support them.
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