Reliable 25 Gigabit Ethernet via Thunderbolt • Hacker News Board

Re: Reliable 25 Gigabit Ethernet via Thunderbolt

#131

Post by MisterTea » Mon, Feb 02, 2026, 4:19 PM UTC

throwaway2037 wrote: post #45

This is an outstanding blog post. Initially, the title did little to captivate me, but the blog post was so well written that I got nerd-sniped. Who knew this little adapter was so fascinating! I wonder if the manufacturer is buying the Mellanox cards used from data center tear-downs. The author claims they can be had for only 20 USD online. That seems too good to be true! Small thing: I just checked Amazon.com: http…

Have you tried eBay? I bought my Mellanox Connect X3 10 Gb cards off there for like $25 years back to build a 10Gb network at home with a Mikrotik.

Re: Reliable 25 Gigabit Ethernet via Thunderbolt

#132

Post by teleforce » Mon, Feb 02, 2026, 4:23 PM UTC

hardwaresofton wrote: post #96

throwaway2037 wrote: post #45

This is an outstanding blog post. Initially, the title did little to captivate me, but the blog post was so well written that I got nerd-sniped. Who knew this little adapter was so fascinating! I wonder if the manufacturer is buying the Mellanox cards used from data center tear-downs. The author claims they can be had for only 20 USD online. That seems too good to be true! Small thing: I just checked Amazon.com: http…

Not much to add here but wanted to agree, this is post was actually hacker news (tm)

You can say that again, classic HN post with Jeff confessing to have bought literally the last adapter with the original posted price.

Re: Reliable 25 Gigabit Ethernet via Thunderbolt

#133

Post by hnuser123456 » Mon, Feb 02, 2026, 4:37 PM UTC

bob_theslob646 wrote: post #109

Please forgive me for my ignorance, but are there currently any ways of being able to write data down at that speed? I see 2026 PCIe 5.0 NVMe advertising theoretical 14gb/s but not sure how feasible even that is.

PCIe 5 drives max out at about 14 GBps (bytes), which is ~112 gbps (bits).

Displayport 2.1 UHBR20 is 80 gbps.

USB4 maxes out at 80 gbps.

As you can see, 1gbps ethernet is starting to look like stone age technology. 2.5gbps becoming the next step seems a bit strange when we were jumping orders of magnitude every few years before. But also, ethernet tends to be used on longer cables than DP or USB, and trying to push it much faster results in exponentially increasing losses to resistance and radiation, the cable starts acting like an antenna even with the twisted pairs. Fiber optics are much better suited to high speed long distance, but too expensive and fragile for consumer use.