Blender crashing when rendering with GPU tiles

I have a very complex scene , that I need to render out an animation for. When I render with progressive refine , it works fine , however, even after 10hrs  @ 20000 samples it is far too noisy and progressive refine does not support denoising. 

I have four GPU's in my PC - three GTX1080s and one GTX1080-Ti . If I enable all four , and render with tiles , the render time is only 2 hours and denoising would tidy the render up perfectly - IF it would work. 

Every time I render with tiles , it gets about 20 mins in and then Blender just vanishes. 

I have tried the scene in both 2.8 and 2.81 and both crash . I have also updated the drivers to the newest Nvidia studio driver , which states that it has been specifically tailored for studio work with programs including Blender Cycles renderer. 

I would also like to try reading the error report which Blender apparently puts out after every crash but I have no idea where to find it. 

Any help would be greatly appreciated. 

  • Markus Berg(thebergh) replied

    Since you say you have a very complex scene, and crazy amount of samples, do you think you could be running out of memory on the gpus?

  • Matthew Fricker(frikkr) replied

    I conisdered that , but in the past when it has happened , Blender has remained open and come up with the error CUDA , out of memory , rather than just instantly shutting down. 

    However , it could well be that , as I have discovered that the scene renders fine with the 1080Ti on tiles , but as soon as I introduce any , or all of the 1080s it crashes. Now the 1080Ti has 11GB VRAM I believe , whilst the standard 1080s only have 8GB . It makes sense that it is the issue , but still seems strange that it does not just stop the render with an error as It has done in the past....

    Thanks for your reply