CPU clock speed versus memory size trade off query

[RacybabeUK]

I am revising for an exam on Friday and cannot find a concise answer to my query that has come up while reading up on CPU clock speeds. The book mentioned that there is a trade off between CPU clock speed and memory size but what is the trade off? My first thoughts are that as the processor speed becomes more rapid the memory access time cannot keep up. Any thoughts on this please?

[doctorgonzo]

Yes, that's true. It may also be referring to the fact that the more memory you have, the longer it takes to access it. L1 and L2 cache on the processor is small, but these days tends to run at the same speed of the processor. System RAM is more plentiful but slower; hard drive space even more so.

[RacybabeUK]

Many thanks for your reply.