What a network card does in a server
A network card, also called a network interface card, NIC or network adapter, is the hardware that connects a computer to a network. It takes data from the operating system, packages it into Ethernet frames and sends it out over copper or fibre, then does the reverse for incoming traffic. In a server, the card also sets how many ports you have, how fast they run, which cables and switches you can use, and how much packet-handling work lands on the CPU.
Most servers include networking from the factory, but on enterprise hardware that onboard networking is usually a removable module rather than chips soldered to the motherboard. That is why the network card interface matters as much as the port speed. An HPE FlexibleLOM card will not go into a Dell daughter-card slot, and an OCP 3.0 adapter will not fit a server designed before the standard existed. Match the interface to the chassis first, then choose speed and port type.
At a glance
Typical deployments
Virtualisation hosts
A hypervisor host needs separate paths for VM traffic, management, live migration and storage. Port count and redundancy matter as much as raw speed: two 25GbE ports split with VLANs can replace a bank of 1GbE links, freeing switch ports and cutting cable clutter. A dual-port card such as the Dell XXV710-DA2 25GbE adapter (00M95) lets you run one port to each of two switches so a switch failure does not take the host offline. Our VMware and Hyper-V server buying guide covers the rest of the host specification.
iSCSI and storage networks
Storage traffic rewards consistent latency over headline throughput. SFP+ or SFP28 ports with short DAC runs to a top-of-rack switch keep latency low, and dedicating ports to storage stops backups or VM migrations from competing with disk I/O. This is also where a converged network adapter earns its place, carrying LAN and storage protocols over the same ports. Check each card's specification for the offloads your storage platform actually uses before you buy.
File, print and branch servers
Plenty of office workloads still sit comfortably on 1GbE. A quad-port copper adapter like the HPE 331FLR quad 1GbE card gives a ProLiant host teaming and separate network segments using the Cat5e or Cat6 cabling already in the building. For a dual-port alternative on the same FlexibleLOM interface, the HPE 368FLR-T fills the same slot with two 1GbE RJ45 ports.
10GbE over existing copper
If your switches have 10GBASE-T ports and the building is cabled for RJ45, a card like the Lenovo X540-T2 dual-port 10GbE card avoids transceivers altogether. The trade-off is heat and power: 10GBASE-T generally runs warmer than SFP+ with DAC, and fanless cards depend on chassis airflow, so check cooling in dense 1U servers. Upgrading NIC speed only pays off when the far end keeps up, so review your network switches at the same time.
Repairs and like-for-like replacement
When an onboard adapter fails, the fastest fix is the same part number. A matching card keeps the same driver, interface naming and firmware behaviour, so the operating system configuration carries on untouched. Search by the spare number on the failed card: the HPE 368FLR-T, spare 872161-001, is a common example on ProLiant rack servers, and the HPE 534FLR-SFP+ 10GbE adapter is a frequent replacement where fibre is in use.
Cisco UCS and mixed estates
Cisco UCS rack servers use their own mLOM form factor, and the Cisco UCSC-MLOM-C25Q-04 quad SFP28 card gives a single host four 25GbE ports. In estates that mix vendors, standardising on one controller family across HPE, Dell and Lenovo hardware keeps drivers and tuning consistent, which simplifies patching and troubleshooting across the fleet.
Why buy from Compuwyze
- 12-month return-to-base warranty on network cards and other simple items, with 3 years on configured servers and workstations
- Free UK delivery on orders over £50
- We aim to ship orders for simple items placed before 2pm on the same day
- UK delivery is normally next working day once your order has shipped
- International delivery through FedEx economy and priority services, usually 2 to 5 days
- 30-day returns, with return shipping paid by the customer
Frequently asked questions
What is a network interface card, and what else is it called?
A network interface card is the component that gives a computer its connection to a network. You will also see it called a NIC, network adapter, LAN card or Ethernet card, and "NIC card" is a common, if doubled-up, term. In servers the names often describe the interface: LOM (LAN on motherboard), rNDC on Dell, FlexibleLOM on HPE, mLOM on Cisco and OCP 3.0 on newer platforms. The HPE 368FLR-T, a dual-port 1GbE copper FlexibleLOM card, is a typical example.
What is the purpose of a network card in a server?
At its simplest, a network card moves data between the server and the network: it handles the physical signalling, gives each port its own MAC address and passes frames to and from the operating system. Server cards go further, offloading work such as checksum calculation from the CPU, supporting multiple queues for virtual machines, and giving you enough ports to separate management, production and storage traffic or team links for redundancy.
How do I know a card will fit my server?
Check the interface first: daughter cards, FlexibleLOM, OCP 3.0, mLOM and PCIe are not interchangeable. Then compare the part number on the listing with your server's documentation or with the card already fitted. For PCIe cards, confirm whether your riser takes low-profile or full-height brackets. Firmware levels on the server can also affect whether a newer adapter is recognised, so it is worth updating the system before fitting a card from a later generation.
Should I choose RJ45 or SFP+ ports?
Choose RJ45 if your switches and cabling are copper and you want to avoid buying transceivers. Choose SFP+ or SFP28 if you need longer fibre runs, lower latency, or lower power per port in a busy rack. Within a rack, DAC cables are a cost-effective way to connect SFP ports to a switch. Whichever you pick, the switch at the other end needs matching ports.
What is a converged network adapter?
A converged network adapter carries ordinary network traffic and storage traffic, such as iSCSI or FCoE, over the same physical ports, often with hardware offload so the CPU does less of the work. It lets you run storage and LAN through one pair of cables per server instead of separate Ethernet and Fibre Channel cards. Support for specific storage protocols varies by card, so check the specification against your storage platform.
Do SFP network cards come with transceivers or cables?
Check the individual product listing to see what is included. SFP-based cards need a compatible transceiver or DAC cable for each port you use, and some OEM and Intel-based adapters are particular about the optics they accept, so confirm that your modules are supported by the card before you deploy it.