Blender caps available threads on multi-core system

Hey all! I recently purchased a used 12-core system (2x Intel Xeon E5645, and loaded it with Centos7 for help with rendering at work. I was hoping that the extra cores would prove it to be powerful enough, despite the fact that the chips are about 5 years old now.

Anyway, I noticed Blender’s thread auto-detect feature only sees 8 of the 12 cores. I did some searching and found that (at one point) Blender had been hard-coded to max out at 8 threads ( At the time the solution was posted, Blender had a BLENDER_MAX_THREADS variable that controlled the cap in the file /blender/source/blender/blenlib/BLI_THREADS.h.


In another file, /blender/source/blender/blenlib/intern/threads.c/, was a similar line:

#define RE_MAX_THREADS 8

Long story short, it appears that code has been updated to:


Which would seem to fix the issue at a quick glance, but the problem still persists - I only see 8 of the 12 cores on my system. Are there other issues with my system that might be causing this to happen?

UPDATE: Running ‘lscpu’ on my machine shows Centos only sees 8 cores as well. I wonder if I need to enable Hyperthreading to get the full 12?

ANOTHER UPDATE: SOLVED! Turned out my BIOS settings were limiting my CPUs. I updated the BIOS and now Blender sees 24 threads!