Just discovered my latency is through the roof, looking for a new ITX MB

So I just ran latency test and discovered my max jitter was 400,000+ on an old Intel Atom D2550. For a while I've thought this wasn't the best board, so I'm looking for a new MB and CPU. I run a 5i25, so I need a PCI or PCIe with PCIe to PCI adapter. I'd prefer 12V, but that's not a necessity. I'd like ITX or smaller so that it fits into the control cabinet without much fuss. I haven't built a PC in 15 years, so I'm way out of the loop. I want to run Mint with LCNC 2.8, the 5i25 has a 7i77, running 3 analog servo drives and an analog VFD for spindle control on a Hurco mill. I'd prefer not to buy another Mesa card (ethernet) unless I have to. The 5i25 works.

Thank you for your help.

You can try to use the RTAI kernel and LinuxCNC from here :
www.linuxcnc.org/temp/
-linux-headers-4.14.174-rtai-amd64_4.14.174-rtai-amd64-3_amd64.deb
-linux-image-4.14.174-rtai-amd64_4.14.174-rtai-amd64-3_amd64.deb
-linuxcnc_2.8.0~pre1_amd64.deb
-rtai-modules-4.14.174_5.2.3-linuxcnc_amd64.deb
Install them by double clicking or using gdebi .

Thanks Tommylight, I'll give this a shot tonight. This is compatible with Mint, yes? I just click through on the mill and install these files?

Yes and yes.

So after all that I still have a latency of 140,000ns without really punishing the system. I just opened this window and youtube. Pretty sure the PC is just shot. At idle jitter is 90k ns

What does
uname -a
in a terminal say?

Linux CNCMill-Mint 4.19.106-rt44-lcnc #1 SMP PREEMPT RT Thu Mar 5 00:02:34 AEDT 2020 x86_64 x86_64 x86_64 GNU/Linux


so it looks like the rtai kernel didn't install

Maybe it did, but it requires holding down shift button while booting to show the grub menu and there choose the RTAI kernel.
Or you can install grub customizer and use that to make the RTAI entry as default. That is not a typo.

Also, I have a conflict installing linuxcnc_2.8.0~pre1_amd64.deb - it conflicts with the current Linuxcnc-uspace installation.

Use synaptic package manager to remove linuxcnc, then install.