Vszerda
Vszerda RTL8125B 2.5G PCIe network connector low profile
Adds a 2.5 Gbps Ethernet port over PCIe 2.1 x1 with a low-profile bracket included
- 5 Gbps Ethernet over CAT5e via RTL8125B chipset
- Low-profile bracket fits slim chassis and standard PCIe slots
- Wake-on-LAN and PXE boot supported for remote management
- Broad OS support from Windows 98 to Linux and macOS
- IEEE 802.3bz and NBASE-T compliant for multi-gigabit networking
What this adapter does
The Vszerda RTL8125B adds a single 2.5GBase-T RJ45 port to any desktop, workstation or server through a PCI Express x1 slot. It negotiates 10, 100, 1000 or 2500 Mbps automatically and includes a low-profile bracket for slim chassis. Driver support covers Windows from ME to Server 2016, Linux, macOS and DOS.
Sustained throughput behaviour
The controller complies with IEEE 802.3bz for 2.5 Gbps over Cat5e or better UTP and maintains full-duplex operation with auto MDI-X. PXE boot and Wake-on-LAN remain active during continuous traffic, while 2.5G and 1G lite modes reduce power draw when the link is idle. Compatible hypervisors include DSM, PVE, iKuai, Unraid 6.9.2, OpenWrt and ESXi 6.7.
The deciding specification
This card uses a PCI Express 2.1 x1 interface, so total bandwidth is limited to one lane at 2.5 or 5 Gbps. Systems without a free x1, x4, x8 or x16 slot cannot install it, and ESXi 7.0 is explicitly unsupported. Buyers needing multi-port or 10 GbE connectivity should select a different adapter.
Highlights
- 5 Gbps Ethernet over CAT5e via RTL8125B chipset
- Low-profile bracket fits slim chassis and standard PCIe slots
- Wake-on-LAN and PXE boot supported for remote management
- Broad OS support from Windows 98 to Linux and macOS
- IEEE 802.3bz and NBASE-T compliant for multi-gigabit networking
Specifications
No published specifications for this item yet.
Questions about this item
Does the RTL8125B card run hot or draw much power when it stays at 2.5Gbps all day?
The adapter uses a PCI Express 2.1 x1 lane and supports 2.5G/1G Lite mode for lower power; no fan is fitted and the board measures 71.5 x 50 x 1.6 mm, so heat stays modest in a ventilated case.
What slot and bracket does my PC need for this low-profile RTL8125B adapter?
It fits any PCIe x1, x4, x8 or x16 slot and ships with a low-profile bracket; a standard-height bracket is not included.
Will the card work in a server that still runs ESXi 6.7 alongside newer Windows 10 clients?
Yes — the RTL8125B is listed for ESXi 6.7, Windows 10 (32/64-bit), Linux and macOS, and supports PXE and Wake-on-LAN across those platforms.
New to this? Which coin should you pay with — what to check, what it costs to pay, and what is never asked for.
Also in this aisle
People compared these
Same shelf, same checkout — eight coins and a 30-minute rate lock.



