E10G42BTDA: Intel Ethernet Server Adapter X520-DA2 Dual-Port 10GbE SFP+ PCIe 2.0 x8 NIC
Also listed as: X520-DA2, 82599ES 10GbE, E10G42BTDAG1P5, 82599ES, X520DA2 · made by Intel
The Intel Ethernet Server Adapter X520-DA2 is one of the most famous and widely deployed 10GbE network cards in history, powered by the Intel 82599ES controller. Renowned for flawless out-of-the-box driver compatibility across Linux, FreeBSD, OPNsense, pfSense, Proxmox, and ESXi, it provides dual 10GbE SFP+ ports over PCIe 2.0 x8. Second-hand market purchasers must verify genuine Intel provenance due to widespread counterfeits, and note that the ixgbe driver requires optics_allow_unsupported_sfp=1 parameter for non-Intel coded transceivers.
Specifications
| Part number | E10G42BTDA |
|---|---|
| Brand | Intel |
| Made by | Intel |
| Type | Network adapters |
| Other numbers | X520-DA2, 82599ES 10GbE, E10G42BTDAG1P5, 82599ES, X520DA2 |
| Status | end of sale |
| Interface | PCIe 2.0 x8 |
| Form factor | PCIe Low Profile |
| Ports | 2x 10GbE SFP+ |
| Speed | 10GbE |
| Generation fit | Legacy PCIe Gen2 and Gen3 servers, homelabs, and firewalls |
About the E10G42BTDA
E10G42BTDA is Intel's legendary Ethernet Server Adapter X520-DA2, powered by the Intel 82599ES 10GbE controller over a PCIe 2.0 x8 bus. Renowned for rock-solid stability and universal driver support across Linux, FreeBSD, pfSense, OPNsense, Proxmox, and VMware ESXi, it remains the most popular dual-port 10GbE SFP+ adapter in homelabs and budget enterprise racks.
Compatibility
Installs into PCIe 2.0, 3.0, or 4.0 x8 and x16 slots. Features dual SFP+ cages supporting 10GbE SFP+ optics and DAC cables. Under Linux (ixgbe driver), non-Intel coded optical modules require the allow_unsupported_sfp=1 kernel module parameter. Low-profile and full-height brackets are supported.
How to identify a genuine unit
The card features an Intel Yottamark hologram on the rear, an Intel branded heatsink, and a label reading E10G42BTDA or X520-DA2. In lspci, it identifies as Intel 82599ES 10-Gigabit SFI/SFP+ Network Connection. Check for genuine Intel hologram to avoid cheap clone boards.
Buying used
Verify genuine Intel provenance, as the X520 is one of the most widely cloned NICs in secondary markets. Check for genuine Intel silkscreen logos and holographic security stickers. Inspect the dual SFP+ optical cages for bent pins and confirm both ports link cleanly at 10Gbps.
Reference prices (last 14 days, updated 2026-10-27)
New: USD 140 (1 sighting, Oct 2026)
Used: USD 45 (1 sighting, Oct 2026)
All sightings
| Seller | Condition | Price | Note | Seen |
|---|---|---|---|---|
| serversupply.com | new | USD 140 | 2026-10-27 | |
| ebay.com | used | USD 45 | 2026-10-27 |
Prices seen on public listings on the dates shown, before tax and shipping. Not an offer.
Fits these models
Equivalent part numbers
- Dell 942V6 Dell Intel X520-DA2 Dual Port 10GbE SFP+ Adapter
FAQ
Why is the X520-DA2 so popular for homelabs and firewalls?
Its 82599ES controller has near-universal driver support and rock-solid stability in FreeBSD and Linux.
Can the X520-DA2 use third-party optical transceivers?
Yes, by passing the allow_unsupported_sfp parameter to the ixgbe kernel driver module.
Buying or selling E10G42BTDA?
New, refurbished or used. Tell us the quantity and condition and we connect you with a vetted reseller in your region, usually within one working day.
Sources
- Intel Ethernet Server Adapter X520-DA2 Specifications, checked 2026-10-27