Schrittmotoren brummen im Stillstand

What are the step time and step space set at?
Does it still loose connection to Mesa when LinuxCNC is running?
Edit,
Check motor wiring, wrong wiring will cause motors to just buzz in place. Disconnected any wire causes the same thing.
Make sure step from mesa goes to step on the drive, misswiring this also causes buzzing in standstill.
Check the drive current is set correctly, to low causes buzzing...

omg it is alive. I turned every BIOS option off that smells just a little bit like "intel" or "power".
Now the ping is around 85us.

Linuxcnc is running stable as long as I dont turn on the motors. When I do so I still get the
hm2/hm2_7i96s.0: Error finishing read!
ITER=5711
from time to time but I was able to set up the basic speeds, ranges and referencing of the axes. I needed some movement of the machine to feel better.

I don't know if and how much time I'll have this week but I will do some switcheroo in the BIOS to figure out what was the problem.

Next step: get finally rid of that finished read error.

My current setup for the axes is:
Driver: MA860H
8x Microstepping (1600 steps per rev)
differential wiring

[JOINT_0]
TYPE = LINEAR
HOME = 0.0
FERROR = 10.0
MIN_FERROR = 1.0
MAX_VELOCITY = 41.666666666666664
MAX_ACCELERATION = 500.0
# Die folgenden Werte sollten 25% größer sein als MAX_VELOCITY und MAX_ACCELERATION
# Bei Verwendung der UMKEHRSPIEL-Kompensation sollte STEPGEN_MAXACCEL um 100% größer sein.
STEPGEN_MAXVEL = 52.08
STEPGEN_MAXACCEL = 625.00
P = 1000.0
I = 0.0
D = 0.0
FF0 = 0.0
FF1 = 1.0
FF2 = 0.0
BIAS = 0.0
DEADBAND = 0.0
MAX_OUTPUT = 0.0
# diese sind in Nanosekunden
DIRSETUP = 10000
DIRHOLD = 10000
STEPLEN = 5000
STEPSPACE = 5000
STEP_SCALE = -1600.0
MIN_LIMIT = -0.01
MAX_LIMIT = 203.2
HOME_OFFSET = 0.000000
HOME_SEARCH_VEL = -5.000000
HOME_LATCH_VEL = 0.100000
HOME_FINAL_VEL = 0.000000
HOME_USE_INDEX = NO
HOME_SEQUENCE = 1

OK, I have installed the probe basic ui and hooked up the tool lengh sensor. I understood the "tool_touch_off" subroutine and measured my first tool. Everything seems to work when I noticed that stepper are making that weird sound when I zoom in the 3D view.
My servo threat is on 2000000 and I get this error:
Unexpected realtime delay on task
0 with period 2000000
This Message
will only display once per
session.
Run the Latency Test and
resolve before continuing.

Did you setup the kernel command line as suggested?
 
That is, what does:

cat /proc/cmdline

report?

cncfraese@CNCFraese:~$ cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-6.3.0-rc5-rt8 root=UUID=87c1cf74-4a2b-4e07-a0b5-5db8f79de404 ro quiet splash intel_idle.max_cstate=1 processor.max_cstate=1 idle=poll intel_idle.max_cstate=1 i915.enable_dc=0

Unfortunately it may be that that PC is just not suited to real time use
(sounds like video interference)

You might try isolcpus in the kernel command line