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Cycles render CPU + GPU computer crash
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System Information
Operating system: Windows 10 Pro 64bit

Graphics card: GeForce GTX 1080 (417.35)

Processor: Intel Core i7 8700

Blender Version
Worked: (optional)

Short description of error
Rendering in Cycles with both CPU + GPU can cause instant computer shutdown.

I can render the problematic scene with only GPU - no problem
I can render the problematic scene with only CPU - no problem
I can run two Blender instances and render one with CPU and the second with GPU - no problem

Exact steps for others to reproduce the error
Based on an attached .blend file (as simple as possible).

I did localize problem in Cycles CPU + GPU rendering with material node "Ambient Occlusion" on some meshes (not all the time).
Different scenario of crashes exists too (common problem is always GPU + CPU rendering).
Scene without node "Ambient Occlusion" can crash too.

  • Open my attached blend file in factory clean Blender
  • in Preferences -> General -> Cycles Compute Device -> Compute Device -> CUDA -> GPU + CPU
  • Render Cycles GPU + CPU, 3000 samples


  • start factory clean Blender
  • set the Render Engine to Cycles
  • Device: GPU Compute
  • Sampling Render: 3000
  • in Preferences -> General -> Cycles Compute Device -> CUDA -> GPU + CPU
  • delete Cube and create UV Sphere
  • apply material with node "Ambient Occlusion" -> Principled Base Color -> Material Output.
  • start rendering
  • instant computer crash

In the problematic scene, when I change the UV Sphere to the Cube, Blender will render OK.

After computer crash, the rendered scene is sometimes corrupted and not possible to open again or "Append" from it to the clean one.



Event Timeline

I couldn't reproduce this on my computer using blender 2.80 (2019-01-12) with the attached file

Operating system: Windows 10 Pro 64bit, 16GB ram
Graphics card: GeForce GTX 1070
Processor: Intel Core i7 3770K

I did render on GIGABYTE GeForce GTX 1070 G1 Gaming and Core i5 2500. However never used this slow CPU for rendering, only GPU and had never crash.

Hopefully somebody with the same configuration as me could test it i7 8700 (non K), GIGABYTE GeForce GTX 1080 Mini ITX 8G (or at least long version).

I could test Core i5 2500 + GTX 1080 once I will install system.

It is possible to catch some log from Blender before crash?

@Marek Trejbal (marek3ball) On Windows Blender doesn't create crash report when a segfault occurs. You can start it from command line though and add the "--debug" flag, this will keep the console open with debug prints. More specific flags are available if detailed information for e.g. GPU rendering is required.

Unless the command save file before crash it will not help.

I did some stress tests with Prime95 cpu benchmark and find out that when I turn off the Turbo Boost in BIOS, it will render the problematic scene.
Now with Turbo Boost OFF, I can render CPU + GPU + run Prime95 benchamrk at the same time.

How is it possible that Turbo Boost have such effect? Power consumption is still around 200W.

@Marek Trejbal (marek3ball) Sounds more like an issue with your OS and drivers or even hardware then.