Editorial, 22 Aug 2026. Specs from maker pages and recent street reports. We have not burned these units in. Affiliate tags are not live.
Buy a new 10Gtek DAC and a named X710. Skip “works great” NICs.
Extends the mystery-10G-card warning in used vs new without rewriting that essay. The buy is a new passive DAC and a card that names the chip. Used random optics and unlabeled NICs stay the skip.
The closet-cable sibling SFP+ DAC for a closet hop already picks 10Gtek lengths. This note is the used-enterprise temptation: a gray “10G card, works great” listing with no chipset. You want Intel X710 / XXV710 or a known Mellanox SKU. You want a new DAC, not a mystery optic from a parts bin.
10Gtek SFP+ DAC 1 m, Cisco-compatible: Amazon ASIN B00WHS3NCA snap $15.99. Other 10Gtek 1 m listings ~$20.99 (CA). 3 m listings ~$28. Intel Ethernet Converged Network Adapter X710-DA2: Newegg snaps $237.22 (14U-0045-00010) and $279.25 (0XM-009Y-00017). ServerSupply new $220. 10Gtek-branded X710-BM2 dual SFP+ on Newegg from ~$165. Passive DAC: no fans. Vendor tables often put X710-DA2 in the few-watt / ~3–6 W band depending on optics. We did not re-measure. Pairs with CRS305, QSW-2104-2S, and MS-01 SFP+.
The short list
| Thing | What it is | Street, 22 Aug 2026 | Buy if |
|---|---|---|---|
| 10Gtek SFP+ DAC 1 m | Cisco-compatible passive DAC. ASIN B00WHS3NCA. | Snap $15.99. | The closet hop. New. Named. Not a used optic. |
| Intel X710-DA2 | Dual SFP+. Named Intel chip. Newegg 14U-0045-00010 / alt 0XM-009Y-00017. | Snaps $237.22 and $279.25. ServerSupply new $220. 10Gtek X710-BM2 from ~$165. | The host needs a 10G NIC and you will only click a listing that names X710-DA2 or X710-BM2. |
Skip
Skip “works great” 10G NIC listings with no chipset. Skip used random optics. We did not quote a used eBay NIC price because we are not sending you there. Skip a long passive if the other end is a NIC — the closet DAC note already warns under 3 m. If you have no cages yet, start with 2.5G copper or the Catalyst myth.
Sources
Amazon B00WHS3NCA $15.99. Newegg X710-DA2 14U-0045-00010. Newegg X710-DA2 0XM-009Y-00017. Intel X710-DA2 product family. Labthrift used vs new mystery-card line. Street moves.