Artefacts in rendering emission shader particles

I’m having a problem rendering some particles which are using an emission shader as their material, see the images below:

These strange square, noisy artefacts appear. It doesn’t happen every frame, maybe just 1 out of 50.

Hardware I’m using is K80 GPU (render farm). I’ve never had problems like this before using the same hardware.

Can you share a scene where the problem appears?
Since your hardware is not very common, it would be good if you share a scene to see if we can reproduce the problem on gaming cards.

Anyway, if the problem still persists on 2.83.9 LTS or Blender 2.91.0 Beta:

You should report the problem. But developers will ask you to share a .blend file where the problem occurs.