Cycles doesn't use 100% CPU while rendering

So I’m rendering all my Blender projects using CPU since I don’t have a fast GPU.
This problem started to occur about a week ago, I didn’t have any problems up until now but Blender is only using about 33% percent and 1.6GHz of 3.3GHz available. It’s using every core but only a third of every core.

I’ve already tried adjusting the tile size or disabling auto-detect, but it didn’t change anything.

Any help would be greatly appreciated; Thank you for your time.

I just had a thought. I have a similar situation when i’m gamin on my pc, its not using the full potential of my gpu. turns out that my cpu is bottlenecking my pc. Definition from google:
‘‘Bottleneck is a kind of hardware limitation in your computer. A bottleneck occurs when the capacity of an application or a computer system is severely limited by a single component. Components that oftenbottleneck are graphic card, processor and HDD.’’


I dont know if that’s the problem here but maybe, just trying to help ;). try monitoring your hardware usage while rendering and if something jumps up to a more or less 100% that may be the problem.

You could try setting thread priority in the task manager. Something else normally in the background might be hogging focus from the OS. Sometimes there’s also settings in power management that may cause problems if the computer detects being idle (no user inputs) for too long.

Could you post a screenshot of your render settings? Also what are you rendering? Is it animation with a lot of fast rendering frames?

Shouldn’t be an issue here. Cycles uploads the whole render kernel to memory, either System RAM when CPU rendering or VRAM when GPU rendering. Perhaps he’s using more memory than his PC has and some of it is being paged on the HDD or SSD, but I’m not sure that would result in lower CPU use.

I’m fairly confident this isn’t a Blender issue, but either an Operating System or hardware issue. With Summer starting to come into full force in the northern hemisphere, I’m thinking your CPU is overheating. It might be automatically underclocking because it’s too hot.