With my 6XEVGA 750 ti SC (No Bios mod, no extra connector, no OC, Max 1320MHz) on LyraREv2 it is 395W In from wall on digital PSU. Windows 8.1 Pro
Quark 420W in from wall
Idle 90W in from wall
Lyra2v2 on the 750ti should do around 5MHASH each with the correct clocks. so your rig does around 30MHASH if you tune it correctly.
The 980ti only does around 18 MHASH with overclocking and costs the same as 6 used ti's.
But the 980ti can of course do much better with the right code..
I currently do 4806 per card or 28836 for the rig. but then I am not pushing my cards. The only thing i have up is the fan speed at about 70% at 53C I am sure I could do more but it is not worth the time at this current pay rate.