High end PC is not the same as "put all you can possibly buy" inside your monster case...
It's more about "can that PC tackle with ease all of your needs".
For example, I consider that for me playing demanding games on a single screen, my i7 930 at 4Ghz and my single 7970 oc'ed are largely into the "high end" department still.
If I had 3 screens, that'd be mid-range cause of gpu lacking.
If I was into CAD design, i'd be in the mid-to-low side cause I could use a 12 thread CPU and more than my miserable 6GB RAM, which however is high-end for gaming as its running 1600 7-7-7-21-1T
I also think that any high-end pc should have at least a decent sata3 SSD that will be able to store all frequenty used applications.
Basically i'm saying what has alrdy been said in previous posts ^^