It's pretty easy to see that any finite machine isn't Turing Complete, because you just ask whether it can compute a function that doesn't fit in its memory. So, for your laptop: define a function that's true on some number larger than would fit in 16GiB (fiddling the definitions as necessary depending on exactly how you define input / output etc.)
As wikipedia says:
> No physical system can have infinite memory, but if the limitation of finite memory is ignored, most programming languages are otherwise Turing-complete.
The convention is to ignore the infinite case, when talking about real systems because a) most things we want answers to are not large enough for this to make a difference and b) otherwise no real system is Turing-complete, and that's not a helpful definition.