RT-Kernel wth MESA-Card?

Hi
I have an understanding problem.
Do I still need an RT kernel if I use MESA cards? The stepping is now generated on the MESA card and therefore the latency on the motherboard should not matter.

Yes real time is required, when controlling a machine

The only time real time is not need is when running a simulator ie: not controlling a machine.

Hi
Thanks for your quick replies.
The background for my question is the following.
At the moment I have a hobby-mill with a running linuxcnc.
I use an extra computer with a parallel interface to steer my mill.
This computer gets older and sometimes it will strike. I hoped that I can use my Desktop-PC with an ethernet MESA-card
as backup Computer. But my desktop computer has a modern linux without rt-kernel. I thing I have to buy a new mobo when my old computer will die.
Best regards
werner