Realtek RTL8127 NIC Performance
We took two NICs, hooked them up “back-to-back” and this is what we saw:
This is reasonably good in terms of performance, we are certainly hitting 10GbE speeds. Something worth noting is that we did this using the card versions of the NICs. We also have a number of systems that integrate these NICs, and so we double-checked our results. We tried PCIe card NIC to the onboard NIC, and onboard NIC to onboard NIC. The results looked almost identical to the above, so it seems not to matter how these are implemented, so long as they are on PCIe Gen4 x1 lanes.
Key Lessons Learned
Let us take a step back for a moment. We have had 10Gbase-T NICs for many years at this point. The Realtek NICs tend not to have the most virtualization features. Support for these in Windows and Linux is ok, but you most likely want to go to Realtek’s site and download drivers today. Many OSes will not recognize these NICs out of the box.
The impact of this NIC is really twofold. First, this is the footprint, and an x1 electrical interface that is ideal to integrate into motherboards. Even the PCIe Gen4 x1 card is a bit awkward. Adding an x1 slot consumes significant motherboard space, so we usually do not see them on mITX motherboards. The package is perfect to integrate onto motherboards that previously had PCIe Gen3 x1 lanes driving 2.5GbE NICs. Having a Gen4 x1 NIC means we effectively get four times the bandwidth due to the better lane utilization.
Perhaps the bigger benefit for the PCIe card is the cost. Folks have given us wildly different pricing, but $10ish for a NIC seems to be common to hear at this point. That means these PCIe cards are $35-45 each. Adding 10Gbase-T for $45 if you have an open PCIe Gen4 x1 slot and around 2-3W of power consumption is awesome.
The bigger challenge is that with an x1 NIC, we are now at the end of the line for 10GbE. With a PCIe Gen5 x1 lane we can support 25GbE, so in the future lanes will be massively underutilized with 10GbE NICs.
Final Words
Hopefully we will see more of these NICs, along with some of the fun derivatives in the next few months. This is one where we are probably more excited for the integrated NICs than the PCIe cards. At the same time, at $35-45 for the NICs this makes the NIC side of adding 10Gbase-T networking very affordable. While we do not get the virtualization offloads and so forth, 10GbE networking is really easy for modern processors to handle. That is why we can see low-power Arm-cores drive 10GbE firewall/ gateway appliances without issue.
Still, for many of our STH readers, these Realtek RTL8127 NICs are going to open up awesome systems.
Where to Buy
If you want to find the cards we purchased and current pricing, you can check out AliExpress affiliate link 1 and link 2.
No legacy test with PCIe 3.0 or even 2.0?
Just double checked. They support full Multi-GbE. 100/1/2.5/5/10. That would make them a good defacto choice for all motherboards going forward allowing for folks to support whatever network they might be running up to 10GbE.
With the outrageous prices of motherboards these days, I would hope that all of the manufacturers include 10GbE as the default going forward.
How about interrupt usage and CPU load with 64byte packets ?
Gen3 and Gen2 x1 do not have the bandwidth for 10G speeds.
I think the idea of many motherboards having this, also given the price of memory and such, it starts to make a lot more sense.
Adrian – on the 64b wait until 2026. We literally just rolled in a giant (well) used Pelican case with big packet generation box that we should have up and running later this week. We still will have some time until we publish results from it, but my hope is to be able to test up to the QNAP 25GbE/ 100GbE with it at 64b line rate https://www.servethehome.com/qnap-qsw-m7308r-4x-8x-25gbe-and-4x-100gbe-managed-switch-review/
All part of the process of getting much better networking reviews.
What about linux kernel support and ASPM support?
I don’t understand how you are getting close to 10 Gbps. Shouldn’t PCIe Gen4 x1 be capping around 8Gbps in each direction? It’s hard to tell for sure since your are not mentioning any exact numbers and the graph is not very granular.
I think I’ll get one of these for my 5950X / X570 desktop. Currently I have a T6 25GbE card in there, and while that card lacks nothing beyond maybe an FPGA, I’ve only got a 10G network and it’s not doing anything even remotely fancy. The single-lane card would move LAN to an otherwise unused x1 slot, freeing up an x8 slot for Thunderbolt.
Ok, nevermind, I guess the 1.97 GB/s of bandwidth in PCIe Gen4x1 is unidirectional.
Patrick,
I know, but it would be interesting to see if the card auto-negs 1G/2.5G/5G or does something completely different when installed into a legacy PCIe slot.
Jeff G your math is wrong. gen4 x16 = over 200Gbps so 200/16 = 12.5Gbps per lane. Or just remember that gen4 x1 is 4GB/s. 4 and 4 to remember