I have 16g i7 cpu RAM but in large assemblies in solidworks is thought to complete command but cpu and memory are more than 50% available.
It is how SolidWorks works in that it cannot take advantages of multi cpus for most operations.
It is like a 400 meter relay at a track meet. A four member team can only run 400 meters slightly faster than a single runner. The first runner runs 100 meters and hands the baton to the next runner who does the same thing until the last person passes the finish line.The 4 runners cannot run their leg of the relay all at the same time.
Not sure what the exact question is. You're unlikely to be using even close to 50% of your available ram (8gb) even in a large assembly. You won't be using anymore than 50% of your cpu when working in the assembly if you're dual core and no more than 25% if you're quad core since modelling opeations are all single core.
My doubt is how to use solidworks all the hardware availability. For the positioning commands will do is slow but the cpu still has free resource.
Solidworks is not designed to take advantage of multi-core CPUs, so you will never come close to maxing it out.
You may need to optimize the way in which you are working with the assembly. https://forum.solidworks.com/docs/DOC-1221 Take a look at the pdf, you may need to change a few settings for example use lightweight, large assembly mode. etc.
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