ANTMINER S5 BULK BATCH 4 1155GH/s x 52  
68.745 BTC
 ( 18247 USD )
Shipping Cost  7.529 BTC
 ( 1998.391 USD )
Total    76.274 BTC
 ( 20245.391 USD

...............................................................................
ANTMINER S5 BATCH 4 1155GH/s  x 52
72.358 BTC
 ( 19240 USD )
Shipping Cost 7.516 BTC
 ( 1998.391 USD )
Total  79.874 BTC
 ( 21238.391 USD )


Where do you see here discount from shipping costs or even  free shipping? Only in your dreams...


Even better. 1000GH/s      0.45W/GHs

Yeah, just going by the 18kW limit posed by the question. Tupsu touched on this already, but even in qty 52 Bitmain is still charging $351 per unit, or $376.03 per unit shipped to the US. You'd only be able to use one coupon though, so if you had 30+ coupons you actually wouldn't save anything ordering 52. You might be able to swing a better deal than the single price, but I'm not sure Bitmain would give you a better price on 30 than they offer on 52.

I won this  SP20 miner. https://bt.irlbtc.com/view/789369.0
cost me only 40USD VAT,  so I can use him to efficacy tests

Just putting this out there, would you not get better efficiency if you run the S5 off 2 PSU's, e.g a 550W PSU for each blade, than run the whole rig off a single 750W/850W/1100W PSU?

1. Throw into that mix the 550W PSU being a server one - smaller (yes), less efficient than a 1100W (no)
2. If we get to the sweet spot being between 750W-850W for the S5, then I can not see how either would be more efficient than 2 550W PSU's, assuming same product line.
3. Then there will be price, I know you can pick up a multi rail 750W PSU for around GBP 50.00 (could be cheaper depending), but you can also pick up a single rail 550W server PSU for GBP 10.00
I think it is both cheaper and more efficient to run an S5 that way .... I am just not sure how the draw at the wall would differ (and that's why I put it out here, been tumbling about in my head for a while now!)

Between 50-85% there is usually low single digit efficiency differences. Not enough to care about really.

Well I prefer to push my SP20 harder now and lower then later (diff jump). It always depends on so much factor ... for me electricity is cheap, so it's a no-brainer (~1100 watt for like 1560GH)

Do not feel obliged to comment. I already got a sensible response.

1. Not sure, it depends on the server PSU. There's a lot of 550W PSUs on eBay that are pulls from the mid-2000s, and they often aren't necessarily any more efficient than an ATX PSU.
2. They wouldn't be more efficient, but they wouldn't be much less efficient. I saw the sweet spot because you then get away from having to use two PSUs with the corresponding extra volume and cable management, and the price per watt is still good. Once you go up over 1000W, the price per watt goes up dramatically.

For example, you can go get a Rosewill Capstone 750W gold supply at Newegg for $90 shipped in quantity, no rebates or other crap. It'll still do 90% efficiency at 550W (DC) output. You could pick up two 550W supplies and be right in the 50% part of the curve, but any two supplies you get for $90 will probably do worse than the 750W supply anyway since you'd really have to shop around or dick around with buying one at a time and using MIRs to get anything other than a Bronze PSU under $50.

3. Server PSUs are a who other matter. I wouldn't even bother with a 550W server PSU, since you can find 800W server PSUs for that price just as easily. You just need to be willing to do some extra work to get them working.