Realtek 8126 5gb Network card - a quick review

Notice: Page may contain affiliate links for which we may earn a small commission through services like Amazon Affiliates or Skimlinks.
MountainBofh

MountainBofh

Beating my users into submission
Mar 9, 2024
420
300
63
I ordered a pair of these on a whim from Aliexpress. https://www.aliexpress.us/item/3256806785910357.html

At $16 per card, I figured why not. I got the cards in, and popped one into my test machine. I used a cheapo ethernet cable to run it into a SFP+ to RJ45 10gb transceiver plugged into my Arista SFP+ switch.

Initially I tried it with Linux Mint running kernel 6.5. No dice, the network controller is too new for the kernel driver.
Next, Debian 12 with kernel 6.7. Also no dice, same issue.

I grabbed the newest driver from Realtek and ran their autorun.sh script, which quickly compiled the proper driver and got the network card up and running.
Card links at 5gb, and iperf3 to my file server gives consistent 4.70gb/sec with zero retransmissions.

Redid the above steps in Debian 12, and got the same results. So their driver at least works ok up to kernel 6.7

I booted into Windows 11, installed the newest driver from realtek, and reran iperf3. Got the same speed, so seeing consistent performance here.

As a final test, I pulled the transceiver from the Arista switch and moved it to my generic realtek switch (4 2.5 ports + 2 SFP+ ports). Same network performance and no issues linking. Then plugged the card into one of the RJ45 2.5gb ports, got a link, and was able to pull 2.5gb without issues.

Summary - performance wise the card delivered 5gb no problem. As I expected, built in OS driver support is poor at this point in time, so you'll need to compile the newest driver off realtek's site (or install the Windows driver as needed). The bigger hurdle will be switch support. I got around this by using the RJ45 to SFP transceiver, but considering the transceiver costs 2x what the network card did, this is hardly a cost effective solution. However with cheap 5gb switches on the way, this may finally make high speed, low power consumption networking a reality.
 
  • Like
Reactions: mach3.2, cageek and blunden
S

sko

Well-Known Member
Jun 11, 2021
399
251
63
You are aware that you can get Mellanox ConnectX-2 cards for ~2/3 of that? Even CX311/312 based cards are often available at the same price as that realtek one...
SFP+ switches are already available extremely cheap - either new "noname" ones or *a lot* of (new or used) consumer/soho/enterprise gear. There's really no reason to throw money into sub-10Gbit gear if 10Gbit is already a *really* old hat, extremely cheap and widely available and properly supported throughout all OS.
 
  • Like
Reactions: BackupProphet
J

janek202

New Member
Feb 4, 2023
27
22
3
Could you please check if it supports ASPM? Are there any issues with Pkg C-states?
 
Last edited:
S

SnJ9MX

Active Member
Jul 18, 2019
187
130
43
sko said:
You are aware that you can get Mellanox ConnectX-2 cards for ~2/3 of that? Even CX311/312 based cards are often available at the same price as that realtek one...
SFP+ switches are already available extremely cheap - either new "noname" ones or *a lot* of (new or used) consumer/soho/enterprise gear. There's really no reason to throw money into sub-10Gbit gear if 10Gbit is already a *really* old hat, extremely cheap and widely available and properly supported throughout all OS.
Click to expand...
wouldn't be surprised if these 5Gb cards take a fraction of the power required for cx-2. for the $5 difference, it could be paid off in a matter of months depending on electricity price

edit: quick search shows 1.7W for RTL8126, 6.4W for CX-2, at $0.15/kWh that is $6.18 per year, more if you also need to cool the resultant heat
 
  • Like
Reactions: blunden
M

marv

Active Member
Apr 2, 2015
157
34
28
40
These chips were supposed to appear a year ago, but it didnt happen due to some stability problems. Any word on whether that problem is fixed and this is new revision, or refurbished old one?
 
MountainBofh

MountainBofh

Beating my users into submission
Mar 9, 2024
420
300
63
marv said:
These chips were supposed to appear a year ago, but it didnt happen due to some stability problems. Any word on whether that problem is fixed and this is new revision, or refurbished old one?
Click to expand...
That is a good question and one I don't have an answer for at this time.
 
MountainBofh

MountainBofh

Beating my users into submission
Mar 9, 2024
420
300
63
sko said:
You are aware that you can get Mellanox ConnectX-2 cards for ~2/3 of that? Even CX311/312 based cards are often available at the same price as that realtek one...
SFP+ switches are already available extremely cheap - either new "noname" ones or *a lot* of (new or used) consumer/soho/enterprise gear. There's really no reason to throw money into sub-10Gbit gear if 10Gbit is already a *really* old hat, extremely cheap and widely available and properly supported throughout all OS.
Click to expand...
Totally different use case, and one that a lot of people here are over looking. I'm testing these cards not for my usage (I'm already well setup for 10gb fiber using a Mikrotik SFP switch), but for scenarios where clients have existing cat-5e cabling in the walls that can't be easily replaced. Also, I suspect that within a few years you're going to see a LOT of motherboards with this controller built in (like how we see most newer boards with 2.5gb built in).
 
  • Like
Reactions: blunden
J

janek202

New Member
Feb 4, 2023
27
22
3
MountainBofh said:
Would lspci show that? If you give me some quick suggestions on checking for the above, I'd be glad to do so.
Click to expand...
Thank you.
"sudo lspci -vvv" should print the ASPM status under LnkCap and LnkCtl sections.

C-states can be checked with "powertop".
 
O

Oshim

New Member
Dec 24, 2024
1
0
1
Hello guys!
Does this network chip have its own chip (cpu)?
Matter being latency. I want to enable its own cpu if it has one so it does not communicate with the main CPU of the system, thus saving on latency.

If interested, the suggestion is as follows:

You need to add value in registry

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters

In the right window:
right click new 32bit DWORD Value name: DisableTaskOffload

DWORD Value: 0 = Use NIC Processor, 1 = Disable NIC Processor

Image


Thanks to everyone who considers a response!
 
Last edited:
You must log in or register to reply here.
Top Bottom