Quote from: MrTeal on October 09, 2014, 02:46:57 PM

Quote from: Bonam on October 09, 2014, 05:52:20 AM

Quote from: MrTeal on October 08, 2014, 03:26:40 PM

I think you're missing the point of the graph. It's purpose is to illustrate, given certain parameters, what the final steady state network hashrate could end up being. Barring large changes in price or available technology, eventually the network will get to the point that even a large operation in a location with extremely cheap electricity will not be able to break even in X days even without difficulty changing.

The assumption is fundamentally invalid because there will always be changes in "available technology". Even once bitcoin mining ASICs reach the cutting edge in terms of modern process size, algorithm optimization, computational efficiency, etc, major companies in larger markets will continue to push the bounds of technology forward and ASIC manufacturers will benefit from these new technologies, releasing better and better products. The cost of a given amount of computing power is cut in half on about a yearly basis. So long as advanced human civilization exists, technology will continue to progress and there will never be a "steady state". And, so long as bitcoin remains valuable enough to warrant anyone to bother mining it with custom equipment, any miner bought at a given point in time will provide less hash rate than a miner bought a year later for the same amount of money. And that makes the graph not applicable in any real situation.

Remember where the discussion originated. I made the claim that even today, many miners fail to ever break even or just barely break even. The graph was posted as a rebuttal to that, to show that in fact capital expenditures are easy to recover and that we are far from the point where that would no longer be the case. But it only shows that in a constant difficulty environment. In a rising difficulty environment, say 10% per period, my statement is closer to the truth, as can be quickly checked with any of the conventional online mining profit calculators. And, said rising difficulty environment is the real world in which miners are trying to make back their investment and profit.

I think there's still room to go in terms of power efficiency, but I don't know how much higher it will go. A lot of it is predicated on price. I honestly don't think there is much left to be done algorithmically to improve efficiency; the simplicity of the SHA256 means it's pretty easy to optimize. There's probably still a good bit of work to do on layout, but even that will taper out as people get designs optimized. Looking at what is currently the best implementation (Bitfury), with perfect scaling he might get ~0.2J/GH on his existing 55nm design shrunk to 28nm.
I personally think the limit of 28nm will be closer to 0.2J/GH than 0.1J/GH. You're being quite optimistic on the cost of computing power halving every year, IMO.

The biggest variable in all of this is price though. It was easy to tape out new 28nm designs and order a bunch of wafer starts when you could charge $5k for a box with <$1k in parts other than the ASIC itself. If you do get someone down to 0.2J/GH, you're already 3x better that anything else on the market at 28nm. Going from there, you're going to be looking at marginal improvements with each new spin. With margins very tight, you need to really look at what kind of income you'll generate in order to justify the cost of the new design.

I take Puppet's spreadsheet to be a simple demonstration tool, I don't think his intention is to imply it's an accurate model. I would say his assumptions are much more sound than your main premise though. If even with free electricity a miner cannot recover their capital cost, NO ONE WILL BUY MINING EQUIPMENT. Sorry for the caps, but this keeps on coming up and it's a fundamental logic flaw. With free electricity your costs of running equipment are negligible. To say that the capital costs will never be recovered assumes that income approaches 0 as the network hashrate approaches infinity.

Answer one simple question, with the assumption that continued increases in difficulty will mean that even people with free electricity can't recovery their capital costs in equipment, who do you think will be buying the ~250PH/s worth of mining hardware necessary to even double the current hashrate?

Puppets tool is not meant to predict when/howfast the difficulty will increase. It's only meant to demonstrate how the parameters affect the difficulty and give you a rough idea of what you would expect if we reached equilibrium and technology stopped advancing.

Of course technology will still advance but it won't be at the current 10%/2 weeks rate. I'd guess ~1%/diff increases if it follows Moore's law.

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If even with free electricity a miner cannot recover their capital cost, NO ONE WILL BUY MINING EQUIPMENT.

Exactly this. Large scale mining operations do not have access to free electricity and need to be earning massive profits if they want to continue spending millions on NRE.

I don't understand how people can say that nobody can make a profit mining because there is some entity out there that will continue adding hashing power far beyond the point everyone is mining at a loss.