How Jeff Geerling hacked 25 Gbps Ethernet onto a Mac Studio

You can push a Mac Studio past its 10 Gbps networking limit, but you will need a soldering iron and a Noctua fan to keep it from melting.

Jeff Geerling connected a 25 Gbps network card to his Mac Studio using a cheap Thunderbolt 3 adapter board and a server-pulled OCP 2 card. Off-the-shelf Mac adapters cost up to $1,099, but this DIY rig cost him $160. To stop the server card from overheating, he 3D-printed a custom fan shroud, soldered an 80mm Noctua fan directly to the adapter's power pins, and updated iperf3 to handle multi-threaded transfers.

Why it matters: Apple doesn't put PCIe slots in the Mac Studio, so upgrading network speeds usually means buying expensive Thunderbolt gear. Geerling proved you can hit 20–25 Gbps—the limit for the Thunderbolt 3 chipset—for a fraction of the price. Real-world file transfers only reached ~1.4 GB/sec read and 1 GB/sec write, which is only slightly faster than built-in 10 GbE.

Here's the gist: enterprise network cards rely on loud server fans for cooling. If you drop one into a tiny desktop enclosure without active airflow, it will cook itself.

All that custom wiring for a small real-world speed boost—but at least he got a good blog post out of it.