Ditto. My Ant farm has been self-sustaining and expanding for just under 2 years now. Yes profits are dropping but so far I have been doing very well. Even bought probably my last 2x s7's last night. For now from here I'll just wait to see what this years miners look like.

thx. We (well, I) am in the process of commissioning a new toy that arrived a week ago http://www.trumpf-laser.com/en/products/solid-state-lasers/short-and-ultra-short-pulsed-lasers/trumicro-series-5000-femto-edition.html to apply my majik touch/insights to with the goal of pushing our systems processing capabilities further.

That sucka costs over $450k and Trumpf has lent it to us for free for at least 6mo to play around with. For our end, so far ~ $120k into a new testbed workstation to use the laser with. Of course their goal is for us to find/improves uses for it so they can sell more. Since each of our systems usually has 4 heads meaning 4 lasers... You get the idea. Knowing of our work with fiber lasers from their subsidiary that supplies them to us it should be a safe bet for them to make. They know our primary customer in Taiwan has very very deep pockets and when we say we can provide systems for them to produce component packing densities no one else can economically reach those pockets open very wide. Only catch is for us to first prove it to them.

 The rest of our lil part of the industry supplying laser micro-machining systems are still a few years behind figuring out how we do what we do so blisteringly fast but nonetheless are catching up so time to leapfrog them once again with beyond bleeding-edge mfg tech

Way OT here... Gotta watch out for the Powers that be....
Unless perhaps Bitmain would like some help in making their miners smaller that is. If so give us whistle  

And thankfully in the US at least is less than the VAT tacked on that most folks across the pond have to deal with.

At this moment income from each of my s7b8 's at work (free electric) is paying just over $8/day so not counting what the Halving will do If I buy a batch 10 today it should ROI in just over 100 days. Yes I know dif rise etc will change that.

That said, for my investment in upgrading s2/3/4/5's to s7's I do not look at per-machine ROI I only look at power consumption/THs and my available BTC to spend at that time.

When I started after about maybe 7-8 months the Ant Pharm was already paid for and from then on was dedicated to paying for upgrading and increasing hashrate. Since then the total miner farm income at any point has covered it all plus paying for quite a few nice toys from what was TigerDirect.

Since current pharm income is now banging around 0.3BTC/day that means I could get another s7 every couple weeks until I run out of available power (close to it already) if I don't mind not increasing the btc 'surplus in my wallet  Not gonna happen soon as have to replenish after buying my last 3 s7's a few weeks ago

Though do gotta say at current price for the batch-10.... maybe just one more? <said the junkie>

At least I eventually got a rig from AMT even if >4months late and by then nearly obsolete tech Most folks didn't or got them without PSU's.

You are right in that as final users of the chips we could/should care less what the physical chip does vs what design simulations (and any pre-order hype) said as long as it performs as advertised with the typical real-world specs when sold.

Just saying that once a chip is on silicon and in production it can then benchmarked to see what the real world performance is. At that  point any difference between initial expectations and physical product is between the chip OEM and foundry to work out. However once engineering samples are released and folks develop reference designs/actual complete miners based on those proven nominal performance specs it is expected that each chip used does all it is supposed to.

Deviation outside of nominal = either the chip vendors having to under-spec the chip to cover slow ones and use more ASIC's in their mining rigs to assure rig performance  (but in turn make for possible OC'ing) or if production tolerances or tweaked performance expectations per-batch get out of hand then just sell the chips like Bitmain did - different miner batch #'s with different advertised performance. btw: Bitmain has/is compensated its customers for the lower than expected performance batch. I still from time to time get a 0.01btc input to my wallet from them over it.

I'm co-founder of and Sr. Engineer at http://www.synchronlaser.com/ so in a way the free electric is part of my comps 14kw of that is concentrated in one area that can tolerate the noise and heat of what is now mostly s7's, the rest is mostly nice quiet s3's in various offices for supplemental heating aka space-heaters along with my 1.2THs (re-branded Dragon) rig I eventually got from AMT. Yes, it is still running perfect 24x7x365 since Aug 28, 2014.

Um, tell that to the customers screwed by AMT/Bitmine.ch over the A1 kerfuffle when it was introduced. Inno's A1 failing to meet design specs cost us final customers 100's of k$ in total or more. For most folks it looks like their money is never to be seen again as the lawsuits are in limbo. And ja Bitmine.ch's horrible board design was the icing on the crap cake.

BirFury, Bitmain, et al care very much about spec as that is what they base their miner designs on, eg how many chips in it running what speed will give us advertised throughput/power usage.

Sure miner chips are vastly simpler than the various processors used in mobile devices. Just simple I/O, bit of memory, coms and the SHA256 cores vs hundreds of I/O and scads of different core components including critical L1/2/3 cache memory. That simplicity should in turn give more good chips vs yield from making mobile processors and their ilk.

Interesting. I was told by my contacts at TSMC that some of their EUV systems from ASML are now running production and were responsible for the improved yields.

As for Apple accepting 40% yield per wafer, for initial runs - yes. That is between them and the foundries. I guarantee that with their clout they are only paying for the good chips and forcing the foundries to eat the scrap.Their only compensation is that Apple and other customers know that initial pricing will be very high to finance the R&D needed and capital equipment costs. Worse for the foundries is pricing is based on a mandatory rapidly downward sliding price per-chip giving foundries great incentive to get better.

The other little niggling bit pertains to the complexity of the chip. As you said, mobile device processors and such have very little to no built-in redundant circuitry to get around mfg defects. Couple with them being highly dependent on timing of the functions and that can explain the oft-cited in the past low yields.

re: production volumes for mining ASIC's, sure they can produce in volume if Bitfury/Bitmain et al pony up the $$. If the simpler chips make it easier to get higher yield so much the better.

50TH of that is at work where I have 20kw of free electricity the rest is at home where the bill is $0.15/kwhr 

No, the foundries *are* using EUV right now despite the problems. I've worked with the companies involved.

Yes until EUV became better last year they pushed double patterning with conventional light sources far beyond what was thought possible but in no way did it work well enough for what the semi biz calls high volume production. TSMC and GloFo both use 13.8nm light sources while Samsung uses 9.5nm light (which is why they are producing actual 14nm junction chips vs 16nm). The talk of pushing back to the 7 and 5nm nodes was referring to that EUV may be able to work there as well instead of hitting a wall at 10nm.

SRAM is only a killer because it is the prime candidate to pack more (junctions) into the smaller area making leakage and bit failure a thorny issue. Couple that with wanting to push hard for ever higher speeds and you have self made (by the industry) issues. For mining ASIC's, as you said they are more robust and if you have a few dead cores, oh well, still a good chip. What has really helped is that only the patterning for making the junctions needs to be done with EUV, by using 20nm features for the intermediate layers the rest of the chip can be built up using very mature processes.

The 40% yield refers to number of good chips per wafer - not cores per chip. As to what is a good chip, it one that meets spec. Preferably with 100% cores active @ stated speed. From there they will start stepping down the grade hopefully mainly by speed capability instead of by dead cores.

I agree. Ya gotta start somwehere.

Back in early 2014 my total initial out-of-pocket was ~$8k. Four thousand of that was wasted for most of the year due the AMT/Bitmine.ch scam, the rest went to Ants. For the most part all BTC earned was re-invested in expanding the pharm/new miners replacing old. I'm now up to 70TH/s with all miners (and the original investment paid back) paid for by BTC earned with a nice kitty left over. It takes time and patience but unless the impending halving hits harder than expected I think it will still pay off to start now.

Another thought. GPU's as in video cards from AMD/nVidia ect? If so look into liquid cooling, there are all sorts of commercial cooling blocks out there for them. Coupled with the right pumps and you can just stick the radiators & fans outside easy peasy with just a small dia hole in the wall for tubing & power to the fans. A helluva lot cheaper than using A/C.

Oh it gets better. I can't ship my RMA'd dead s7 hashboard to Bitmain because of the Spring Festival. The RMA letter says no one will be there to receive shipments until it is over... Glad it's 'only' ~1.5TH currently missing from that miner for over a week now.

For general info on the light source being used and its current status https://www.gigaphoton.com/en/news/3770 Note the date of the release.
They mention hitting a 24hr benchmark but that was an extended test run on a prototype and do not mention that it was test run only. That time between rebuild has not yet hit the foundries floors. btw: Gigaphoton and 1 other vendor makes the system which incorporates modules from other suppliers. Both use the same laser source and basic process to generate the EUV from their interaction with tin droplets.

One good sign of the various foundries confidence that the current tech used to generate EUV will be viable is that the sole supplier of the laser system used in it spent 70M euro's last June on an expansion to dedicated to make the lasers needed. http://optics.org/news/6/6/31. Has a good is basic description of how the EUV light is generated as well.

For info on TSMC's 16nm pr http://www.tsmc.com/english/dedicatedFoundry/technology/16nm.htm
Main consumers of TSMC's production http://www.tsmc.com/english/dedicatedFoundry/technology/application_specific_platform_solutions.htm Note that boutique ASIC's (eg for miners) don't even make the list unless maybe they fall under Power IC.

From 6mo ago, a hint at one of the players that have been footing the bill to reach 16/14nm chips http://wccftech.com/tsmc-begins-volume-production-16nm-finfet-nvidia-pascal-gp100-gpu/ It is only due to folks like them that targeted mid-volume high-end commercial/consumer use pricing has become available. Also one guess what fruity company has bought up almost all the current 16nm production capability of TSMC leaving far less available for miners (so far).

One other bright light at the end of the tunnel: keep in mind what foundries like TSMC, GloFo, and Samsung (Intel and IBM don't count here) consider when talking production volumes. Those are the ONLY foundries able to produce high volumes of 16/14nm chips. Period. Talk several hundred million to around 3/4 billion or more chips per month and you have their rapt attention. They won't even talk to you about 'boutique'' runs of only a million or so per month. I can't see the combined demand from BitFury and Bitmain being more than around a few hundred million chips/mo at best once things are proven out. But, with the processes getting better, miner ASIC's are able to tag along in many of the production steps and that translates into a lot of available custom chips space per step. Hopefully by now BitFury is up to full wafer status (with the attendant ~40% yield per-wafer). With Bitmain probably not far but silently behind???

All that said and done, it will certainly be interesting to see how BitFury's chip comes out!

I agree that blowing the heat outside along with a dedicated (and filtered) inlet from the outside is usually the best solution.

As for your situation, remember that normal AC unit ratings are based on keeping a room at a comfortable temp and having enough overhead for the AC unit to cycle on and off. If you allow the room to get up to say 85-90F (I do and my BTC miners are happy with it) use that as the temp setpoint and as long as you don't mind paying the electric bill for the AC compressor running non-stop then your 32kBTU system may be adequate especially in cooler climates/winter. Also, if you are working with a HVAC contractor on the cooling, mention the ability to have a higher air temp feeding the rigs. How high? That you have to test to find out what keeps rig temps at safe levels. That changes the cooling needed equation a lot.

90% yield?  
That is WAAAAAY off base. That yield is common for higher nodes like 28nm on up but currently 16/14nm production yields are around 40% good dies and lower. They only began to hit 40% late last year...

Now the foundries are of course trying to get better but the processes are still under development. Biggest issue is the EUV light source used for the photo lithography. That monstrosity is still pretty hairy to run and is in no way capable of running 24x7. Is more like 8-20hrs followed by around 6 hrs to a full day of cleaning/realignment/process verification before starting another run of chips.

The math is:
   BTU/hr=Watts x 3.4129
   1 Tonne=12,000 BTU/hr

So for 12kw load you are producing 40954.8 BTU/hr or 3.4129 Tonne of heat to be moved.

Interesting. Too bad the seller didn't provide more info in the input connections. I am guessing that it uses either an external milli-ohm high current sense resistor or more likely a current transformer. The seller should tell us that and if said parts are supplied...

As for exposed connections: Of course they are. It is a panel meter made to be mounted in a control box...
Being able to monitor 220v is a plus because a) Many countries use that as the normal mains voltage and b) most high power loads (eg PSU's) run better on a high line.

Keep in mind that computer PSU's are made to supply 12v or slightly more. Very few can be throttled lower. The nature of delivering power over wire means that by design a (computer) PSU should only need to compensate for voltage drops over the wires. As a result there is little to no downward adjustment possible without modifying the feedback circuit.