latency spike up need help

Recently, i get a new PC with this config:



After installing ubuntu 16.04, realtime preempt-rt 4.9.84 kernel, and linuxcnc, i try test latency then it gives me a very disappoint number:


The latency spike up random, I tried many solutions:
1: Disable SMI control -> doesnt work
2: Disable ACPI and usb legacy support in BIOS
3: Disable core and hyper threading, my PC can run a few minutes with low latency then spike up random.
After it spike up, i try click "Reset statistcs" on latency-test but it still keep that high value

This is the first time i cant fix latency by above solutions. Are there any solutions that i can try? please give me some. thank you

Did you disable all CPU speed switching/power management
in the BIOS (Limit C states to C1 max etc)?

Try this:

wiki.linuxcnc.org/uploads/07_rtai

You have to disable power saving options and check for SMI issues.
Also download the Wheezy version of Linuxcnc and make a bootable USB, use it to boot the computer and check the latency. RTAI version might work better on that PC.

you can try to get smictl to help you find a good solution

Thanks all for help guys,

Today i found out in BIOS there is a "SMI lock" in chipset section. After enabled it latency seem work ok.The smictl maybe doesnt work in this PC. I will try more test to confirm it.

After reseting PC, latency spike up again