Vray volume grid artifacts/low res/noise how to improve quality?

[KushKush]

I've made a simple render representing Fumefx grid render to the left and VrayVolumeGrid to the right. It seems that I get a lot of grain on the volume grid, and some artifacts as well. I used dome light without a hdri map with default settings. I've double-checked the VrayVolumeGrid documentation and made some changes accordingly. In the volume grid, I have disabled the light cache option, in the rendering section step size is 50% and shadow lowered to 50% (down from 100%). *Edit*, Increasing resolution in the grid section of VVG does not have any effect.
Any ideas about what I've done wrong?

[KushKush]

Anyone?
I'll try to clear myself, Why smoke on the right(darker one) has grain inside it while the smoke on the left(white) does not? How do I rid from the grain?

[^Lele^]

Reset the Step and shadow step settings to their default, it ought to render with more definition.

[KushKush]

I've done a reset to the step size and shadow but it haven't solve the issue, What do you mean by "render with more definition"? Increasing scale inside fumefx simulation?

[^Lele^]

look here