I just thought I would share a nice fact about the Asus Z790 Hero and its last PCH connected PCIe slot. Fun fact you do not have to use the Asus add in card for bifurcation, I bought a dual U.2 to pcie x8 adapter and enabled x4 x4 in the bios to create a 905P raid 0 array for my windows install.
I am also trying to run an intel 25Gbits/s nic in the second x8 pcie slot, xxv710 da2 but I am struggling to get 25Gbits/s send speeds from my machine to the Truenas scale iperf3 server (running iperf3 with the reverse will get me 17Gbits/s or so rather than the 9 Gbits/s I’m seeing when sending from my desktop to the server)
Strangely, when using a regular old samba share on my Truenas I can get the 25gbps both ways…
Just thought I would share about the bifurcation working with an amazon u.2 adapter… The Q1T1 performance doesn’t improve much from using Intel VMD Raid … but the latency stays low which is nice. If you have any ideas about getting full 25Gbits/s iperf3 results both ways please share.
I have an asus z790, but I haven’t been able to get bifurcation working. Could you share which dual U.2 to pcie x8 adapter you used and screenshots of your bios changes?
This is the card that I bought on Amazon for dual u.2
I’m using two Optane 905p’s.
You have to have the card in the bottom most pcie x16 slot (G4) and there is a setting in the bios that sets that slot to x4/x4 bifurcation. It is located at
It’s called intel vmd in the bios. There is a level one video talking about it for the z690 boards if I am not mistaken.
Basically you enable the vmd thing for the cpu, and then reboot the bios… when you re enter bios there will be a vmd setup option and you can make your raid array.
