CPU temperature high when rendering with the GPU I tested a cycles render in 2.8 and my cpu temps were really high like 90 degrees high.

I then tested a cycles render with my GPU instead of the CPU, although my GPU temps remained low the CPU temps got really hot again.

So if my settings are to render with the GPU why would my CPU be doing any work and still getting hot?

How can I isolate my renders to just the GPU, keep in mind I am setting the render settings to GPU render but my CPU still putting in work evidently. 

Which doesn't make sense if i'm using the GPU for renders. NM i was about to add a screenshot and realized when i select GPU it becomes grayed out so evidently a AMD RX580 is not compatible with blender.



Do I need to do some additional setting up somewhere within blender? Also my drivers are all up to date, as for the cooling I need to purchase a after market cooler anyway, right now I'm just using the stock cooler that came with my Ryzen 5 2600 a  Wraith Stealth Cooler which does pretty well with everything else except cycles renders. I also have some Artic MX-2 thermal compound I been meaning to apply maybe that will help a little better over the pre-applied compound. But I've seen other posts where people mentioned cycles making CPU temps jump real high [with good coolers] so idk. I've included a pic to show you cycles grey's out when I select GPU render.
Turn off the CPU in the GPU render by going into Preferences > System, and under the CUDA Settings, uncheck the CPU.

I noticed this, too. I'll say that, under the same load, with similar effects and raytracing options, Blender renders, CPU, GPU, or shared, run hotter than in other software, for me.

Blender renders hit 90+ degrees after five or so minutes. Cinema 4D doesn't really go beyond 84 degrees.