RCT ADP-1258H PCIe 2.5Gbps Ethernet Network Adapter

At a Glance

• Adds a 2.5Gbps Ethernet connection to a compatible computer
• Realtek RTL8125B network controller
• PCI Express host interface
• One RJ45 Ethernet port
• Supports network speeds up to 2.5Gbps
• Backward compatible with 1000Mbps, 100Mbps and 10Mbps Ethernet
• Automatic link-speed negotiation
• Standard and low-profile mounting brackets included
• Compatible with full-size and small-form-factor computers
• Supports selected Windows, Windows Server and Linux systems
• Green link and orange activity indicators
• Cat5e or higher network cable required for 2.5Gbps
• Compact 30g expansion-card design

Short Description

The RCT ADP-1258H is a PCI Express Ethernet network adapter that adds wired-network speeds up to 2.5Gbps to a compatible desktop computer, workstation or server.

It uses the Realtek RTL8125B chipset, supports automatic negotiation with 10Mbps, 100Mbps and 1000Mbps networks, and includes both standard and low-profile mounting brackets.

Why Choose This RCT

The RCT ADP-1258H provides a practical upgrade for computers limited to standard Gigabit Ethernet or systems without a working onboard network connection.

Its 2.5Gbps capability provides additional bandwidth for compatible local networks, network-attached storage, large file transfers, media workflows, gaming and live streaming.

Backward compatibility allows the card to operate with existing 10Mbps, 100Mbps and Gigabit Ethernet equipment while providing 2.5Gbps connectivity when connected to compatible network hardware.

Both standard and low-profile brackets are included, making the adapter suitable for a wider range of desktop, workstation, server and small-form-factor chassis.

Recommended Use Cases

• Upgrading desktop computers to 2.5Gbps Ethernet
• Small-form-factor computers
• Business workstations
• Home-office computers
• File servers
• Compatible Windows servers
• Network-attached storage access
• Large local file transfers
• Gaming computers
• Live-streaming systems
• Media-production workstations
• Replacing a failed onboard Ethernet connection
• Multi-Gigabit home and office networks

Product Description

The RCT ADP-1258H PCI Express 2.5G Ethernet Network Adapter adds a high-speed wired-network connection to a compatible computer through an available PCI Express slot.

It uses the Realtek RTL8125B chipset and provides one RJ45 Ethernet port supporting network speeds up to 2.5Gbps.

Automatic negotiation allows the adapter to operate at supported speeds of 2.5Gbps, 1000Mbps, 100Mbps or 10Mbps, depending on the connected switch, router, network cable and other networking equipment.

The card supports IEEE 802.3bz 2.5GBase-T together with established 10Base-T, 100Base-TX and 1000Base-T Ethernet standards.

Additional standards include IEEE 802.3az Energy Efficient Ethernet, IEEE 802.3x flow control, IEEE 802.1p traffic prioritisation and IEEE 802.1Q VLAN support.

Green and orange LED indicators provide visual information for network link and activity status.

Both standard-height and low-profile mounting brackets are supplied, allowing installation in compatible full-size and small-form-factor computer chassis.

Key Features

• PCI Express Ethernet network adapter
• Realtek RTL8125B chipset
• One RJ45 network port
• Maximum network speed up to 2.5Gbps
• Supports 2.5GBase-T Ethernet
• Supports Gigabit Ethernet
• Supports 100Mbps Fast Ethernet
• Supports 10Mbps Ethernet
• Automatic link-speed negotiation
• IEEE 802.3 support
• IEEE 802.3u support
• IEEE 802.3ab support
• IEEE 802.3bz support
• IEEE 802.3az Energy Efficient Ethernet
• IEEE 802.3x flow control
• IEEE 802.1p traffic prioritisation
• IEEE 802.1Q VLAN support
• Green link indicator
• Orange activity indicator
• Standard-height bracket included
• Low-profile bracket included
• Windows support
• Windows Server support
• Linux support
• Compact 30g design

Specifications

Supported Network Standards

The RCT ADP-1258H supports:

• IEEE 802.3: 10Base-T Ethernet
• IEEE 802.3u: 100Base-TX Fast Ethernet
• IEEE 802.3ab: 1000Base-T Gigabit Ethernet
• IEEE 802.3bz: 2.5GBase-T Ethernet
• IEEE 802.3az: Energy Efficient Ethernet
• IEEE 802.3x: Flow control
• IEEE 802.1p: Network traffic prioritisation
• IEEE 802.1Q: VLAN tagging

Network Speed Requirements

To establish a 2.5Gbps connection, the complete network path must support 2.5G Ethernet.

This includes:

• Network adapter
• Computer and PCI Express interface
• Ethernet cable
• Router or network switch
• Network-attached storage or destination device
• Operating system and driver

A Cat5e or higher-rated Ethernet cable is required for 2.5Gbps operation.

If the connected equipment does not support 2.5Gbps, the adapter can automatically negotiate a supported lower speed.

Hardware Installation

Installation requires access to the inside of a compatible desktop computer, workstation or server.

Basic installation process:

1. Shut down the computer.
2. Disconnect the computer from mains power.
3. Remove the chassis side panel.
4. Locate a compatible available PCI Express slot.
5. Install the required standard or low-profile bracket.
6. Insert the network card firmly into the PCI Express slot.
7. Secure the bracket to the chassis.
8. Replace the chassis panel.
9. Reconnect power and start the computer.
10. Connect a compatible Ethernet cable to the RJ45 port.

Installation should be performed by someone comfortable working with internal computer components.

Driver Installation

Windows 10 and later may automatically detect the adapter and install a compatible driver.

If automatic installation does not occur, install the appropriate driver from the supplied driver media.

Drivers can also be downloaded from the Realtek support website by selecting the driver for the RTL8125 network controller and installed operating system.

The correct driver must be installed for full network performance and feature support.

Compatibility

Suitable for selected compatible:

• Desktop computers
• Business workstations
• Windows servers
• Small-form-factor computers
• Full-size computer chassis
• Motherboards with an available compatible PCI Express slot
• 10Mbps Ethernet networks
• 100Mbps Ethernet networks
• Gigabit Ethernet networks
• 2.5G Ethernet networks
• Cat5e, Cat6 and higher-rated Ethernet cabling

Supported Operating Systems

Officially listed operating-system support includes:

• Windows 7 32-bit and 64-bit
• Windows 8 32-bit and 64-bit
• Windows 8.1 32-bit and 64-bit
• Windows 10 32-bit and 64-bit
• Windows 11 32-bit and 64-bit
• Windows Server 2008
• Windows Server 2012
• Linux kernel up to 4.15

Driver availability and compatibility should be confirmed for operating-system versions or Linux kernels outside the listed range.

Important Compatibility Notes

• The computer must have an available compatible PCI Express slot.
• This is an internal expansion card and cannot be connected through USB.
• The computer must be powered off and disconnected from mains power before installation.
• A 2.5G-capable switch, router or directly connected device is required for a 2.5Gbps link.
• Cat5e or higher Ethernet cabling is required for 2.5Gbps operation.
• Actual network throughput will be lower than the negotiated link speed.
• Internet speed cannot exceed the speed supplied by the internet service provider.
• The adapter cannot upgrade other network equipment that supports only Gigabit or slower Ethernet.
• The correct operating-system driver must be installed.
• Linux support is officially listed only up to kernel 4.15.
• Compatibility with newer Windows Server versions is not specified.
• Wake-on-LAN, PXE boot and jumbo-frame support are not specified.
• Professional installation is recommended if the user is unfamiliar with internal computer hardware.

What’s in the Box

• RCT ADP-1258H PCI Express 2.5G Ethernet Network Adapter
• Standard-Height Mounting Bracket
• Low-Profile Mounting Bracket
• Driver CD
• Quick Installation Guide

Warranty

One-Year RCT Manufacturer Carry-In Warranty

Sustainability

Support for IEEE 802.3az Energy Efficient Ethernet allows compatible network equipment to reduce link power consumption during periods of lower network activity.

The adapter can add faster wired networking to a compatible existing computer without requiring replacement of the complete system.