Hi @Arnar Helgi Adalsteinsson and @Balduin Allrgg :) Ok, we've finally got to the bottom of this and think we have fixed it in the pre-release version of v017 which we want to release really soon. I would very much like to offer both of you the chance to test it now, however, so that we can verify that you can both use your GPUs.

The issue was that, we had an error in our code that sets what render devices to use. It was a subtle error that only showed up if you disabled the GPUs in the user preferences in blender on the slave nodes. If you had them enabled, then it would seem that CR would work.

Anyway, we fixed the error and now you can select your GPUs to render no matter what the user preferences setting.

So, a huge THANK YOU! To both of you for reporting and sticking with us despite having a frustrating problem, thanks to your persistence (esp @Arnar Helgi Adalsteinsson for the many posts!) we've found a very subtle bug that we didn't pick up on our systems, cause we always have the GPUs enabled in user preferences.

It would be awesome if you guys wanted to try v017, so please reply to this thread if you do and I'll find a way to get the new build to you. It works for both 2.78, 2.79b, 2.79 daily and 2.80 beta (tested with 2.80.53) versions of blender.

All the best

:D

Hey guys, nice thread you got going here - props to Arnar for the testing :D

I guess I have run into the same problem. CUDA problems. I am using a desktop machine with 1070 and a laptop with a MX150 I guess. Did some testing and found out the desktop machine just rendering via CPU - GPU was sitting at 0% load all the time (CPU 100%). Combined render took some 2:10min while single render on the desktop took just under 1min.

Tweaked the tile sizes to match the "ideal" tile size I tested earlier on every individual system. (256*256 on the 1070 and I guess 128 on the MX150). Still no improvement.

After that I was a bit frustrated and took a break, restarded everything and so on ... Eventually I got back into the settings and just unchecked the CUDA device - suprisingly my GPU starts working. Overall I got around 47-49 seconds combined render, both machines set to CUDA and both machines unchecked CUDA checkboxes and both machines got their individual ideal tile size set.

By the way my goal was to set everything up to use my desktop as renderer, to accalerate rendertimes while working remotely.

Hope this helps, might be a bug with the "inverted checkboxes"?