On Friday, we setup six machines to act as our render farm for a short (3000 frame) animation. All machines were loaded from a single saved blend file on a network drive. Five were Windows machines running blender 2.78a/b and one was a Linux box running 2.74. The blend file is set to render at 100 samples. Output was set to .png files with 95% compression.
All machines rendered over the long weekend.
This morning I found that the frames written by the Linux box (2.74) were all significantly larger than the frames from the other machines (~5k vs ~3k). Looking at them, the reason was obvious: they are all much noisier than the others.
I might have expected that between 2.74 and 2.78, the time it took to render 100 samples might have improved, but I wasn't expecting the noise of 100 samples to change much.
My question is this: What is the source of the differences in noise between these two versions?
Thanks in advance!