Question 2.5Gbe on Asus Prime B350M-A
Question 2.5Gbe on Asus Prime B350M-A
Hi,
I'm facing a problem with getting 2.5GbE to work on my PC.
I have a fiber connection of 2.5Gbps to the house, a 2.5GbE router, and a network switch with short Cat 7 cables.
One other PC in the house is connecting fine at 2500 Mbps, so the network side seems fine.
My own PC isn't reaching that speed—only 1000 Mbps.
I replaced the old 1Gbps NIC with a RTL8125 2.5G-1t-X1 NIC, but it still only connects at 1000 Mbps.
After downloading and installing the drivers from Realtek, I rebooted and still got the same speed.
I confirmed the drivers were installed correctly.
My PC details:
- Model: ASUS Prime B3500M-A
- BIOS version: 6232
- Processor: Ryzen 1700X
- RAM: 32GB
- Operating system: Windows 11 Pro
The new 2.5GbE network card I just installed in the PCIE X1 slot is working, so it might be something else.
I also tested a Cat 6 cable from the working PC to mine—it still only reached 1000 Mbps, so that’s not the issue.
Swapping the cable between devices didn’t help either.
It seems the motherboard (ASUS PRIME B350M-A, PCIe 3.0) might not support 2.5GbE on the PCI Express X1 lane.
PS: I’ve also asked if anyone knows how to fix this or if my motherboard can handle it.
Welcome to the forums, newcomer!
First, turn off the onboard NIC in BIOS. Next, remove all drivers linked to Realtek networking adapters, then install the newest drivers for your NIC through an elevated command—right-click the installer and select Run as Administrator.
Do you have a link to the exact card you bought?
The new 2.5Gbe network card I just got fits into the PCIE X1 slot.
Your board has two PCIe 2.0x1 slots; which one is being used? Also, do you have an iGPU on your Ryzen processor? What is the brand and model of your discrete GPU?
Thank you for your response. Before proceeding, I will disable the onboard nic as requested.
I am using an ASUS ROG GTX1060 6B with the RTL8125-2.5G-1T-X1 NIC installed in PCIEX1_2. The X1_1 slot is unavailable because it's occupied by the GTX1060.
The RTL8125-2.5G-1T-X1 NIC comes from Amazon.
Drivers from 10gtek.com direct to the Realtek site.
I have tested both the Win10/Win11 Auto Installation Program (NDIS) and the Win11 Auto Installation Program (NetAdapterCx).
I have turned off the onboard Realtek NIC. All drivers were removed using Device Manager, including hidden entries, and then the Realtek driver 1125.22.1118.2024 was installed from the downloaded driver pack Install_PCIE_Win11_11022_03202025. After rebooting, the link speed remains at 1000 Mbps.
Although I guess you run the risk of messing up drivers can you try the card in the other pc that has the native 2.5g port. This is almost looking like a defective card.
Maybe this is a sign that you really don't "need" 2.5g. Most families can easily get by with 100mbps. Things like netflix 4k only use 30mbps and having more does not make it run better or faster. The only thing really high bandwidth helps with is reducing the download time for large files. It all depends on how many hours per day/month you are downloading stuff. It comes down to how many dollars per minute of time saved is worth it to you.
BUT you paid for a 2.5g nic and it should function at 2.5g. Speed negotiation is done on a very low level with voltages and resistances, this process is designed into the chip when it is manufactured. It is not really something a driver would do, the driver can attempt to force a slower speed but generally you want to leave in auto mode.
This is almost always the port or the cable...most times it is the cable. There are strange cases where some nics will not work with some switches/routers but those turned out to be a manufacturing error.
Consider trying different cable options. Just because it functions on one device doesn't guarantee the cable's quality. Various machines handle out-of-spec cables differently. There are many counterfeit cables available today. The flat ones, in particular, often fail to meet certification requirements for Ethernet cables. You don't need anything special—Cat5e works, but it must be genuine copper wire with a size of 22-24 AWG.
I suggest using a USB-C to 2.5gbe adapter. PCIEx1 lacks the necessary speed for 2.5gbe connections. With USB-C, you'll achieve the required bandwidth.
My entire home network now supports 2.5gbe, and two computers connected via USB-C are performing flawlessly without any problems.
Regarding your current setup, I’ve noticed Windows 11 tends to be overly persistent in selecting drivers. It often grabs a driver it believes is correct, even after you install new ones and remove old ones. This issue didn’t exist with older versions of Windows.
In a workplace environment with multiple users, switching to Windows 11 required manually forcing the right driver. You can extract the *.inf file from the manufacturer’s archive by unzipping the driver package. If it’s an *.exe, you might be able to use 7zip to unzip it and then open the inf file.
Then:
Device manager
, right-click on the existing entry,
Update driver,
Browse my computer...
...
Let me pick
...
Check disk,
Navigate to the driver’s folder,
Select its inf file,
Open
, OK
Using this traditional approach is more reliable. Uninstalling and reinstalling drivers doesn’t always succeed in Windows 11, as I’ve experienced.
Thank you for your messages, appreciated a lot.
I recently received some high-end Cat 8 (40Gbps) cables from Amazon, and I connected one immediately and achieved a speed of 2500 links.
I hope the updated drivers and new cables improve performance further.
You were fortunate. Most cat8 cables are counterfeit. They are primarily available from specialized dealers who also offer gear with 40gbit ports. These products are extremely costly since manufacturers with the capability to produce 40gbit equipment don’t consider adding extra $100 here and there. No retailer selling cat8 on amazon provides proof of certification that confirms the cables are genuine. Basically, sticking to cat5e or cat6a is the way to go. Cat6 is suitable for 10gbit applications, while cat6a is typically chosen only when it’s more affordable than cat5e, but it offers no significant advantage on its own. Cat6 was once considered a dead standard before its release—it was designed to support 1gbit over two pairs, yet no manufacturers embraced the protocol. Marketing teams will continue misleading customers.