something wrong there, a 980 should do x3 750ti, maybe not optimized code for maxwell 2.0, notice nits5 at 99%, that's x3 750ti, the other are not well optimized for sure

maybe the 980 is at default , not oc'd

so 140w for 6.6M on x11 vs 2.5 750ti to obtain that, but you need 150w , also for every 1 rig with 980(at full tdp usage) you need 3 750ti, they are better just for this, but the price is a big no no for now