If limited to 18,000 watts, one can obtain more hashing power with the S5 versus the SP20.
One single SP20 @ $479.00 without shipping [1,700 GH/s @ 1200 watts = .705 watts per GH]
One single S5 @ $370.00 without shipping [1,155 GH/s @ 590 watts = .510 watts per GH]
Let's say power limitations at your location is 18,000 watts:
18,000 watts / 1,200 watts = 15 SP20's x 1,700 GH/s = 25,500 GH/s (25.5 TH/s)
18,000 watts / 590 watts = 30 S5's x 1,155 GH/s = 34,650 GH/s (34.65 TH/s)
Without going any further with comparisons on ROI, one can easily conclude the S5 is easier to achieve ROI than an SP20. This is based off the price of one single unit. If one wishes to compare based on bulk pricing, they must use both bulk package prices [SPT's 15 x SP20's versus BITMAIN's 52 x S5's]. Even if one wishes to choose the bulk price of 15 x SP20's versus the price of one S5, it would still be more worth while to get the S5 at this point in time. The main reason why it would be worth it IS TO KEEP FROM LIMITING THE AMOUNT OF HASHING POWER I CAN HAVE WITH THE LIMITED AMOUNT OF WATTS AVAILABLE TO MINE.
If limited to 18,000 watts you will have approximately 36% more hashing power with the S5.
Just saying...
This is not true. If power is limited, buy more SP20
1x SP20 1000GH/s
0.45W/GHs Can the S5 do this? No.
I am happy that I bought 2015-01-26 at night three S5 for 3.983 BTC ( Today it costs 4.894 BTC)
But I bought later on the same day 3x SP20 for 3.954 BTC , and it was a much better deal. 1
BTC=303USD
3x SP20 3 TH/s 0.45W/GHs total 1350W
3 x S5 3,45TH/s 0.51WGH/s total 1750 W
450GH/s more costs me every hour extra 400W
nearly 300 kw / 30EUR per month, But only produces 0.0122 x 0.45x 30=0.165
BTC per month