i know i know, different power, it's still thin ice.. really falls on the lines of small farm or expandable farm. 750ti's are great if kept within one mobo where everything was snagged at a savings, doing a 10 mobo rig with 750tis becomes a different story
the second you try to get a few megahashes, even at 0.15 the extra hardware will cost you enough to offset the savings..
$340-420- 940kh/s 300w @ 0.15kWh =0.47..... $32.4month x 12 - $388.8 yr of power
$450-510 - 990kh/s 180w @ 0.15kWh =0.28........... $19.5month x 12 - $234 yr of power
$154.8 power savings - $90 initial hardware cost = $64.8 savings per year
You'll save $64.8 , thats not bad, but if you expand the hashrate you won't save anything.
6x450kh/s 270's will be 8 750ti's doing 330kh/s or 9 at 300kh/s or 11 at 250kh/s
clock those 270's to hit 480-500kh/s and your talking about 2 extra mobo, cpu, ram, and multiple power supplies to match the hashrate so the savings wont be there.
EVEN if the 270's scale to tier 2 pricing, there is a big chance a lower hashrate at tier 1 will still cost more with the added hardware
5x 270 @ $175=$875 doing 480kh/s = 2.4mh/s
8x 750ti @ $165=$1320 doing 300kh/s = 2.4mh/s
$445 in gpu costs, factor in reliable mobo,cpu,ram, and psu and power saving is last thing on your mind
gets real bad each megahash it grows Edited by INCREDIBLEHULK - 3/16/14 at 2:26pm