Used Envato Template and some of the project won't run on

It might help if you actually read the online help on basics about how AE previews actually work rather than simply assuming AE would play everything realtime straight off the bat. Likewise, since you haven't offered a link to the original download source we have no idea what the actual requirements for the project are, which no doubt the original author has mentioned on the page. For all we know this could be a specific effect acting up because you modified the template or something along those lines. No, it very likely has nothing to do with hardware nor obscure 3D render settings, it just boils down to your inexperience and thus inability to interpret such issues and act accordingly. Again, reading the help might actually be a smart thing to do and you may even be able to figure things out yourself. Otherwise you have to make an effort and provide much more info despite or exactly because of being a bloody beginner.

Mylenium