**Intel X520-DA2 10GbE NIC**: Provides robust and reliable networking capabilities, essential for high-speed data access and transfers. Link Speed Negotiation, which handles intermediate speeds—automatically switching between 100Mbps, 1, 2.5, 5, and 10Gbps—is NOT standard to all NICs, and if a NIC claims this feature, determine which speeds it supports; look into product specifications to confirm. Intel X540-T2 is a solid and widely supported 1 and 10Gbps NIC for cheap ($75 shipped from reputable eBay seller TheArtofServer), while the next gen Intel X550-T2 features link speed negotiation at all the speeds mentioned earlier ($160 shipped). Look for YottaMark or similar to confirm it's not a knockoff (and double check MAC address with the manufacturer).