Unfortunately I was not able to render with my GPU, but not because of the previously mentioned memory issue. The error I received was: CUDA Error: Launch failed in cuCtxSynchronize()
It actually occurred about halfway through the render on one attempt too. Browsing online this seems to be a current issue that the developers are still trying to figure out. I’ve submitted a bug report in order to give them another point of data, but until it gets solved I will likely have to use my CPU for the rest of this section.
I do believe it has to do with the light paths, as until this section it wasn’t an issue. My video drivers have not been updated in a while, so it was most likely a change in what I was doing in blender. Hopefully this helps some others that might run into the issue. And if anybody happens to see a fix for this problem appear I would love to know.
Are you using Blender 2.78? I had lots of crashing issues when doing the fluffy bunny and rendering in 2.77. I finally just used the render in viewport and upped the passes by a bit. Swapping to 2.78 I haven’t had a problem. But, then again, I am running a Mac and it seems to run best rendering in CPU.
Hi! No I’m on 2.77. Didn’t realize a 2.78 had been released. I’ll go download that and maybe try to do the same failing render tonight with my GPU to see if the issue reproduces.
EDIT:
Gave it a go with 2.78, I’m still running into the issue. every once in a while it will render a section or two before giving me that error. Now though I am occasionally seeing the memory error pop up instead. It may just be that my scene is too busy. I do have a LOT of grass in it.
Sorry 2.78 didn’t solve the issue but, I do think you are right with all the hair and particles to that particular project is going to cause some issues regardless. I will try to suggest something better next time
Something that I tried, and I think that it helped, was to decrease the tile size.
Initially I was at 512x512 and I hit the error that needed the registry hack, then rebooted, and then tried the render again. Failed with the same error as this thread. Closed blender, reduced the tile size to half at 256x256, and things seemed to have worked.
Took longer to render, but much better than it would be using the CPU.
Here’s my scruffy bunny, he’s had a hard life, so don’t make too much fun of him:
I am having the same error. I have tried reducing my tiles, and it still gives the error. I tried updating to Blender 2.78b and updated the nvidia drivers to 369.30.
Thank you so much for bringing the thought about light paths up! I had the same cuCtxSynchronize() error with this scene and I lowered the light paths to Max 8 from like 128 and the Max bounces from 12 to 8 and now I can render the scene!
but, I do think you are right with all the hair and particles to that particular project is going to cause some issues regardless. I will try to suggest something better next time 
