Modern miners can do the same thing as theethlarementPill by setting straps to I believe 2. 1080 and 1080TI with GDDR5X can see big jumps in performance using those straps.I've never mined with an 1080 or 1080ti, so take this with a grain of salt, but MH/sec number DO vary, but not by a whole lot. Varying by 5MH/sec is a lot. 0.5MH/sec variance is fairly normal.
Did you use the "OhGodAnEthlargementPill"? You need to use that on a 1080ti card.