This is an outstanding blog post. Initially, the title did little to captivate m...

kohlschuetter · 2026-02-01T15:00:48 1769958048

Thank you!

I think, tragically, the blog post has caused this price increase.

The offers on Amazon are most likely all drop shippers trying to gauge a price that works for them.

You might have better luck ordering directly from China for a fraction of the price: https://detail.1688.com/offer/836680468489.html

addandsubtract · 2026-02-02T14:28:14 1770042494

AliExpress sells them, too, which is much more accessible for anyone living in the EU.

Lammy · 2026-02-01T22:17:11 1769984231

> The author claims they can be had for only 20 USD online. That seems too good to be true!

In my experience, the cheap eBay MLX cards are DellEMC/HPE/etc OEM cards. However I also encountered zero problems cross-flashing those cards back to generic Mellanox firmware. I'm running several of those cross-flashed CX-4 Lx cards going on six or seven years now and they've been totally bulletproof.

geerlingguy · 2026-02-01T15:16:10 1769958970

I saw the blog post last week and immediately bought the last one on that Amazon listing for the original price... hopefully they restock soon!

I'm going to try a couple other fan assisted cooling options, as I'd like to keep the setup reasonably compact.

I just ran fiber to my desk and I have a more expensive QNAP unit that does 10G SFP+, but this will let me max out the connection to my NAS.

kohlschuetter · 2026-02-01T15:48:23 1769960903

Be sure to test this adapter on iPad Pro, just for kicks (yes it works!)

Although I managed to panic the kernel a couple of times without the extra heatsinks on...

buildbot · 2026-02-01T15:35:17 1769960117

I believe the author is talking about the OCP (2.0) network card itself, that these adapters internally. The OCP nics are quite cheap compared to pcie - here’s 100GBE for 100! https://ebay.us/m/HMQAph

kohlschuetter · 2026-02-01T15:44:48 1769960688

This 100GbE card is an OCP 2.0 type 2 adapter, which will _probably_ not work with the PX PCB since that NIC has two of these mezzanine connectors, and PX only one.

What also may not work are Dell rNDC cards. They look like they have OCP 2.0 type 1 connectors, but may not quite fit (please correct me if I'm wrong). They do however have a nice cooling solution, which could be retrofitted to one of the OCP 2.0 cards.

I've also ordered a Chelsio T6225-OCP cards out of curiosity. These should fit in the PX adapter but require a 3rd-party driver on macOS (which then supports jumbo frames, etc.)

What also fits physically is a Broadcom BCM957304M3040C, but there are no drivers on macOS, and I couldn't get the firmware updated on Linux either.

buildbot · 2026-02-01T16:15:05 1769962505

That’s a good point to note! I think the stacking height would matter, but in theory the single connector is still 8x pcie and should link without the upper 8x lanes connected.

Spec for reference, I’m not 100% sure. https://docs.nvidia.com/nvidia-connectx-5-ethernet-adapter-c...

Palomides · 2026-02-01T18:05:15 1769969115

you can get a 100Gb normal pcie card like a MCX416A for less than $100 if you're willing to flash them

nunez · 2026-02-01T17:54:29 1769968469

$285 is still an AMAZING price for 25GbE ethernet over TB4. I paid $200 for the Sonnet TB4 10GbE adapter.

hardwaresofton · 2026-02-01T21:54:57 1769982897

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

teleforce · 2026-02-02T16:23:58 1770049438

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

MisterTea · 2026-02-02T16:19:28 1770049168

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.