Hello- Question: 
     I have a dual core processor, and when I increase "render on multiple threads" to 2 threads and monitor the cpu usage it stays at a %100 usage, not dipping below at all.  When rendering on 1 thread it stays around %58 or so.  I am aware that engaging both cores on 2 threads does utilize the processor to a higher degree, but I am wondering if this may harm my processor, create excessive heat, or anything that may damage my pc?

Thanks !!!

Generally speaking, I would not worry about that, unless you live in a very hot place. Your PC is designed to operate at 100% CPU usage and still dissipate enough heat to keep within the permissible operating temperature range. You may hear the processor fan increase in speed after a little while rendering - that's normal. Just make sure the airways are kept clear.

Assuming it's not a notebook, if it's more than a few months old and in a place with a lot of dust (e.g. if near or on the floor) I would suggest you open it up and (carefully!) clear out all the dust, especially from the processor heat sink and the processor and case cooling fans. You'll soon find out how often you need to do this.

It's incredible how quickly the grunge builds up even in what seems to be quite a clean environment. It's especially bad for smokers, even if they do not smoke at the workplace.

thanks for the info!!!

it is a notebook, fairly new so lets hope the dust level is low.

Ah, a notebook - sorry about my wrong assumption! Many notebooks have the air intake underneath, and (pretty obvious, I know) these should not be used on your lap or any other soft surface that would block it.  

But I've seen many a so-called "laptop" computer with its cooling air intake on the underside! 

Izi

I wouldn't worry too much about the CPU usage going to 100%, it is designed for any kind of usage up to 100%.