by 1-200 mhz oc. do you mean base or boost clock?
as with boost, pascal usually does another 4-500 easily (over base clock).
and boost is what matters, as its basically the card maxing its clock to the highest possible within the limits set by nv (tdp/power/voltage/temp) and the chip itself, to gain fps.
its like a car changing gears automatically to keep it at optimum rpm (that produces the best power/torque ratio).
with afterburner you can max out the settings for power/temps and voltage, and the card will boost to whatever max clock is possible.
almost every pascal chip i ran, got 1950-2100 Mhz boost, while only gaining about 50-100 MHz max boost when applying additional (manual) mhz.
most of the time not really stable, which is both the good and the bad with boost 3.0
it already makes every chip boost very close to the max it can do (no matter the silicon lottery so to speak), but it also takes a bit away of what can be done manually.
but for most users, its an easy/quick/safe way to max out the cards performance, without killing the card or adding "stress" (watch the temps tho), by basically moving 3 sliders in afterburner to "max"..
this way you can either get a bit more stable fps/higher min frames, or crank up settings without change in fps.