Mellanox ConnectX-2 EN and Windows 10?

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New Member
Dec 3, 2020
I just wanted to thank you for your great post and solution.
I had the same issue with MNPA19-XTR connected to Intel X520-2 (2 port SFP+).

I had the MNPA19-XTR installed on my desktop connected to one of the ports of the Intel X520-2 on a server machine.

After a couple of jperf tests I was not getting any speed greater than 7Gbps. Just to confirm your solution I went to my MB BIOS (ASUS MAXIMUS_XI_HERO) and changed the speed of PCIE from X2 to X4 and voila i tested and got the full 10Gbps speeds.

For people with the same issue make sure you follow the steps below:
1-If you are using any PCIE anything other than the first PCIE on you MB make sure you have the full speed enabled.
In my case my GPU was located in PCIE16_1 and the NIC was in PCIE16_3.

View attachment 12730
Here is how to enable it in you ASUS bios:

View attachment 12733

2-I installed latest driver 5.50.14688 and it gave me full speed:
View attachment 12731

3-Under performance make sure to select single port traffic or single stream traffic then hit Run Tuning and restart computer.

4-Under advanced:
Interrupt Moderation---->Disable
Jumbo Packet---->9014 (this could be different but i matched it with the highest value on my server Intel X520-2 NIC)

5-Receive Buffers and Send Buffer---->4096 or to its maximum value.

7-Make sure to assign static IP on each NIC.

8-Add the IP address and name of the target machine to the Host file on windows. Let me know if you have questions on how to do this (this will force windows to use the 10gb and not the 1gb LAN speed).

6-Use iperf or jperf or RAM disk to test the speeds. Below are my results from Jperf:

bin/iperf.exe -s -P 0 -i 1 -p 5001 -f g
Server listening on TCP port 5001
TCP window size: 0.00 GByte (default)
OpenSCManager failed - Access is denied. (0x5)
[392] local port 5001 connected with port 53662
[ ID] Interval Transfer Bandwidth
[392] 0.0- 1.0 sec 1.07 GBytes 9.21 Gbits/sec
[392] 1.0- 2.0 sec 1.13 GBytes 9.71 Gbits/sec
[392] 2.0- 3.0 sec 1.15 GBytes 9.86 Gbits/sec
[392] 3.0- 4.0 sec 1.15 GBytes 9.85 Gbits/sec
[392] 4.0- 5.0 sec 1.15 GBytes 9.86 Gbits/sec
[392] 5.0- 6.0 sec 1.15 GBytes 9.87 Gbits/sec
[392] 6.0- 7.0 sec 1.15 GBytes 9.88 Gbits/sec
[392] 7.0- 8.0 sec 1.15 GBytes 9.89 Gbits/sec
[392] 8.0- 9.0 sec 1.15 GBytes 9.86 Gbits/sec
[392] 9.0-10.0 sec 1.13 GBytes 9.72 Gbits/sec
[392] 10.0-11.0 sec 1.14 GBytes 9.75 Gbits/sec
[392] 11.0-12.0 sec 1.15 GBytes 9.86 Gbits/sec
[392] 12.0-13.0 sec 1.14 GBytes 9.80 Gbits/sec
[392] 13.0-14.0 sec 1.14 GBytes 9.76 Gbits/sec
[392] 14.0-15.0 sec 1.14 GBytes 9.80 Gbits/sec
[392] 15.0-16.0 sec 1.14 GBytes 9.83 Gbits/sec
[392] 16.0-17.0 sec 1.15 GBytes 9.89 Gbits/sec
[392] 17.0-18.0 sec 1.15 GBytes 9.90 Gbits/sec
[392] 18.0-19.0 sec 1.15 GBytes 9.90 Gbits/sec
[392] 19.0-20.0 sec 1.14 GBytes 9.75 Gbits/sec
[ ID] Interval Transfer Bandwidth
[392] 0.0-20.0 sec 22.8 GBytes 9.80 Gbits/sec

All the credit goes to mfgmfg for his/her great post and solution!!!!!
Thanks again for this.

I'm having issues with my ConnectX-3's from ebay (ocp mezzanine), one card would only run at 2.0 x2 (in a 2.0 x16, running at x4 slot) and 3.0 x2 (in a 4.0 x16, running at x4 slot)


Active Member
Jun 18, 2014
What is the best version of the driver to be used in Windows 10 now in Dec 2020? With the move to Nvidia, I don't see the driver, and Windows installed 5.50.14695.0. (2019)


New Member
Aug 14, 2021
Hi, I wanted to ask if anyone has found ConnectX- 2 - rev.C1 drivers that work with Windows 11 (x64). I was trying many versions:
  • most did not install (with occasional BSOD (it is green in W11 by the way)
  • the ones that did install did not make any change I have Code 43 in windows drivers still
I apreciate any advice

HW codde (HP 518001-001 516937-B21)