--- product_id: 83883544 title: "ConnectX-4 Lx EN Network Adapter (MCX4121A-ACAT)" brand: "mellanox" price: "677 zł" currency: PLN in_stock: true reviews_count: 5 category: "Mellanox" url: https://www.desertcart.pl/products/83883544-connectx-4-lx-en-network-adapter-mcx4121a-acat store_origin: PL region: Poland --- # 25.6 Gbps ultra-high throughput PCIe x8 interface for seamless integration Open Compute Project form factor for modern data centers ConnectX-4 Lx EN Network Adapter (MCX4121A-ACAT) **Brand:** mellanox **Price:** 677 zł **Availability:** ✅ In Stock ## Summary > 🚀 Elevate your data center game with Mellanox ConnectX-4 Lx EN — where speed meets smart innovation! ## Quick Answers - **What is this?** ConnectX-4 Lx EN Network Adapter (MCX4121A-ACAT) by mellanox - **How much does it cost?** 677 zł with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.pl](https://www.desertcart.pl/products/83883544-connectx-4-lx-en-network-adapter-mcx4121a-acat) ## Best For - mellanox enthusiasts ## Why This Product - Trusted mellanox brand quality - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Key Features - • **Multi-Host Magic:** Revolutionize your rack design with multi-host tech that maximizes ROI by slashing CAPEX and OPEX. - • **Plug & Play Simplicity:** Effortless installation with automatic OS recognition—get up and running faster than ever. - • **Blazing 25.6 Gbps Speed:** Experience lightning-fast data transfer that keeps your virtual machines and storage humming without a hitch. - • **Universal Compatibility:** Smart interconnect works flawlessly across x86, Power, ARM, and GPU platforms—future-proof your infrastructure. - • **Virtualization Powerhouse:** Optimized for virtualized overlay networks, enabling more VMs per server with ultra-low latency. ## Overview The Mellanox ConnectX-4 Lx EN Network Adapter (MCX4121A-ACAT) delivers industry-leading 25.6 Gbps Ethernet throughput with ultra-low latency, designed for Open Compute Project 2.0 form factor. Featuring PCIe x8 interface and multi-host technology, it optimizes data center ROI by enabling advanced rack designs and supporting diverse compute platforms including x86, Power, ARM, and GPU. Ideal for virtualized environments, it boosts network performance and maximizes VM density per server. ## Description With ConnectX-4 Lx EN, server and storage applications will achieve significant throughput and latency improvements resulting in faster access, real-time response and more virtual machines hosted per server. ConnectX-4 Lx EN for Open Compute Project (OCP) specification 2.0 improves network performance by increasing available bandwidth while decreasing the associated transport load on the CPU especially in virtualized server environments. Moreover, ConnectX-4 Lx EN introduces the multi-host technology, which enables a new innovative rack design that achieves maximum CAPEX and OPEX savings without compromising on network performance. Review: Simplest installation experience you could possibly expect - Installation literally couldn't be simpler. I popped one of these into a PowerEdge R340 and another into an R720xd with zero fussing from either machine's BIOS (but if you're still cheaping-out by not buying the sliding rails, stop that. Go buy the rails with this, so that you can install them while you have that honking beast pulled out. Then, at least next time, you can enjoy the benefits of civilized rack life). Debian and BSD bare-metal recognized this card immediately. No driver install or configuration of any sort was required. It was 100% automatic*. Next, I popped in a couple of Cisco-branded 10Gbps fiber transceivers and some LX cable and they were chatting like old friends. Benchmarks between servers on the same network chatting via a Cisco 3850 (one having a trunk interface, the other an "access"-type) showed transfer rates getting very close to 10Gbps. I think it was 9.8-something Gbps. Very nice! I'm aware that procedure probably sounds really difficult to the average person. But I assume that if you're spending a portion of the precious time you have left on Earth reading reviews on a Mellanox card, you're quite far from average in more ways than one! It's ok, man. You're among family here. We understand. Now stop stressing, buy the card, and be happy. * OK, I'm lying, you do of course have to configure the network address and all of that on the interface, but I'm ASSuMEing that you know that to be true of any card you get. Review: Bad firmware - Card came with incompatible firmware. Packaging looked new or possibly refurbished, however on two systems (Win 11, and RHEL 9) the card was getting only 1 GbE link. I had to manually find the driver on NVidia's website and download the correct firmware and burn it to the card using their terminal utility. The firmware that was on the card was a version that was not documented as released or in beta, NVidia provided feedback that it is highly suspicious. ## Features - Open compute project form factor - Industry-leading throughput and low latency for web access and storage performance - Maximizing data centers' return on investment (ROI) with multi-host technology - Smart interconnect for x86, Power, ARM, and GPU-based compute and storage platform - Cutting-edge performance in virtualized overlay networks ## Technical Specifications | Specification | Value | |---------------|-------| | ASIN | B011HVAZ78 | | Best Sellers Rank | #190 in Internal Computer Networking Cards | | Brand | Mellanox | | Built-In Media | Mellanox network adapter | | Color | Assorted | | Compatible Devices | Desktop | | Customer Reviews | 3.8 out of 5 stars 9 Reviews | | Data Link Protocol | Ethernet | | Data Transfer Rate | 25600 Megabits Per Second | | Global Trade Identification Number | 07290107197861 | | Hardware Interface | PCIE x 8 | | Item Type Name | ConnectX-4 Lx EN Network Adapter | | Item Weight | 0.18 Pounds | | Manufacturer | INGB9 Music Vendor Code | | Mfr Part Number | MCX4121A-ACAT | | Model Number | MCX4121A-ACAT | | Unit Count | 1.0 Count | | Warranty Description | Unspecified | ## Product Details - **Brand:** Mellanox - **Color:** Assorted - **Compatible Devices:** Desktop - **Data Link Protocol:** Ethernet - **Data Transfer Rate:** 25600 Megabits Per Second - **Global Trade Identification Number:** 07290107197861 - **Hardware Interface:** PCIE x 8 - **Item Weight:** 0.18 Pounds - **Manufacturer:** INGB9 Music Vendor Code ## Images ![ConnectX-4 Lx EN Network Adapter (MCX4121A-ACAT) - Image 1](https://m.media-amazon.com/images/I/612n71ocDLL.jpg) ![ConnectX-4 Lx EN Network Adapter (MCX4121A-ACAT) - Image 2](https://m.media-amazon.com/images/I/61wMYcPhIuL.jpg) ![ConnectX-4 Lx EN Network Adapter (MCX4121A-ACAT) - Image 3](https://m.media-amazon.com/images/I/51uOlokfGAL.jpg) ## Questions & Answers **Q: Can a unifi SFP cable be connected to this card directly?** A: If you mean the copper SFP28 DAC cable, then yes. I am currently using that. For a fiber cable, you need a transceiver. **Q: Does this come with a low profile adapter?** A: Yes. **Q: I have a qnap 873e w/qxg-10g1t add-in. will the mcx4121a-acat 25gigabit ethernet card support this using cat7? what speed could i expect?** A: This NIC uses SFP28 adaptor. If you use SFP+ transceiver with 10G base-T, you will get 10G speed **Q: Does this item ship with both tall bracket and short bracket ? Or only with tall bracket, as in the picture ?** A: Both ## Customer Reviews ### ⭐⭐⭐⭐⭐ Simplest installation experience you could possibly expect *by A***T on February 27, 2025* Installation literally couldn't be simpler. I popped one of these into a PowerEdge R340 and another into an R720xd with zero fussing from either machine's BIOS (but if you're still cheaping-out by not buying the sliding rails, stop that. Go buy the rails with this, so that you can install them while you have that honking beast pulled out. Then, at least next time, you can enjoy the benefits of civilized rack life). Debian and BSD bare-metal recognized this card immediately. No driver install or configuration of any sort was required. It was 100% automatic*. Next, I popped in a couple of Cisco-branded 10Gbps fiber transceivers and some LX cable and they were chatting like old friends. Benchmarks between servers on the same network chatting via a Cisco 3850 (one having a trunk interface, the other an "access"-type) showed transfer rates getting very close to 10Gbps. I think it was 9.8-something Gbps. Very nice! I'm aware that procedure probably sounds really difficult to the average person. But I assume that if you're spending a portion of the precious time you have left on Earth reading reviews on a Mellanox card, you're quite far from average in more ways than one! It's ok, man. You're among family here. We understand. Now stop stressing, buy the card, and be happy. * OK, I'm lying, you do of course have to configure the network address and all of that on the interface, but I'm ASSuMEing that you know that to be true of any card you get. ### ⭐ Bad firmware *by T***R on October 20, 2025* Card came with incompatible firmware. Packaging looked new or possibly refurbished, however on two systems (Win 11, and RHEL 9) the card was getting only 1 GbE link. I had to manually find the driver on NVidia's website and download the correct firmware and burn it to the card using their terminal utility. The firmware that was on the card was a version that was not documented as released or in beta, NVidia provided feedback that it is highly suspicious. ### ⭐⭐⭐⭐⭐ Best high speed high end network card. *by S***L on March 7, 2021* I installed it in a RHEL 7 system and it drivers detected the card without any issues. ## Frequently Bought Together - Mellanox ConnectX-4 Lx EN Network Adapter (MCX4121A-ACAT) - 10Gtek 25G SFP28 SFP+ SR Transceiver, 25GBase-SR Duplex LC MMF Optical Module for Mellanox MMA2P00-AS, 850nm, DDM, up to 100m - 10GTEK 25G SFP28 SFP+ DAC Cable - 25GBASE-CR SFP28 to SFP28 Passive Direct Attach Copper Twinax Cable for Cisco SFP-H25GB-CU2M, Ubiquiti UC-DAC-SFP28, Supermicro and More, 2-Meter(6.6ft) --- ## Why Shop on Desertcart? - 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016 - 🌍 **Shop Globally** — Access 737+ million products across 21 categories - 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price - 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members) - 🔒 **Secure Payments** — Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.pl/products/83883544-connectx-4-lx-en-network-adapter-mcx4121a-acat](https://www.desertcart.pl/products/83883544-connectx-4-lx-en-network-adapter-mcx4121a-acat) --- *Product available on Desertcart Poland* *Store origin: PL* *Last updated: 2026-05-25*