# When build lighting one cpu used

**URL:** <https://forums.unrealengine.com/t/when-build-lighting-one-cpu-used/416224>\
**Category:** Rendering\
**Tags:** bake, building-lighting, unreal-engine, Lightmap, question\
**Created:** [February 2, 2018, 1:31pm UTC](https://forums.unrealengine.com/t/when-build-lighting-one-cpu-used/416224 "2018-02-02T13:31:52Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![ming\_qi](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@ming\_qi](https://forums.unrealengine.com/u/ming_qi)\
**Post date:** [February 2, 2018, 1:31pm UTC](https://forums.unrealengine.com/t/when-build-lighting-one-cpu-used/416224/1 "2018-02-02T13:31:52Z")

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The computer has two cpu and each cpu has 24 cores.The problem is when build lighting (bake lightmap) only one cpu working in full ,the anther is idle.

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**Author:** ![Sardorian](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Sardorian](https://forums.unrealengine.com/u/Sardorian)\
**Post date:** [February 2, 2018, 2:15pm UTC](https://forums.unrealengine.com/t/when-build-lighting-one-cpu-used/416224/2 "2018-02-02T14:15:55Z")

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Go to editor preferences=\>lighting builds=\> tick Enable multithreaded light encoding and multithreaded shadowmap encoding

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**Author:** ![ming\_qi](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@ming\_qi](https://forums.unrealengine.com/u/ming_qi)\
**Post date:** [February 9, 2018, 3:06am UTC](https://forums.unrealengine.com/t/when-build-lighting-one-cpu-used/416224/3 "2018-02-09T03:06:00Z")

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Actually,epic hasn’t implement this function on the windows platform.  
There’s something need to do :Engine\Source\Runtime\Core\Private\Windows.

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**Author:** ![ming\_qi](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@ming\_qi](https://forums.unrealengine.com/u/ming_qi)\
**Post date:** [February 9, 2018, 3:07am UTC](https://forums.unrealengine.com/t/when-build-lighting-one-cpu-used/416224/4 "2018-02-09T03:07:17Z")

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It doesn’t work actually,and i find the reason.  
Thanks for your answer.