Dave you would think that, but its not the case. I can introduce the artifacts simply by upping the noise frequency on the volume noise that is plugged into the blob map of the particle cloud. If I lower it they go away.
It must be something with the noise and the mental ray.
Murambi - Have a quadro 2700 in my laptop, a quadro 1700 (I think) in my workstation at work and an ATI 3850 at home. And if I am honest I see virtually no difference with any of them unless the scene gets really heavy in the viewport then the rank would be 1. 2700, 2. ATI, 3. 1700.
"No pressure, no diamonds" Thomas Carlyle