Price IS IRRELEVANT. All that matters is price/difficulty.
Nitpicking, but those two statements contradict each other. Price is relevant if price/difficulty is relevant.
True. It would be more accurate to say price ALONE is just as irrelevant as difficulty alone.
Either way, I know what you mean, and I agree to an extent. Except, price/difficulty isn't a perfect relationship. There will be more people mining, relative to the price/difficulty ratio, at a lower price, than there will be at a higher price. That is because everyone only has a certain amount of efficiency. There are only so many miners with free electricity, and beyond that, there are only so many miners with electricity at $0.4/kwh, etc, etc.
So, difficulty will be lower at lower prices, but will be reduced at a slower rate than price is reduced. If priced is reduced by a factor of 10, difficulty may only be reduced by a factor of 8.
While there isn't a 1:1 correlation and there is a lag between movement in price and movement in difficulty as a miner it is still price/difficulty that determines you profitability.
I do agree that it is rather silly to pick a specific price that your own mining operations will cease to continue, simply because that would imply knowing what the difficulty will be at that price
So much better poll would be what price/difficulty will you be forced to quick.
Converting units it is sometimes easier to look at USD per day per GH/s since it takes both price & difficulty into account but is more tangible. "If I have 1 GH/s I get x".
Bitcoinx makes some nice charts. I wish it was in USD per GH/s instead of 100MH/s but just multiply by 10.
It is easy to determine your breakeven.
Operating Cost per Day per GH/s = 24*(Electrical rate)/(MH per W)
So if you have $0.10 per kWh and an efficient rig of say 2.5 MH/W then operating cost = 24*(0.10)/2.5 = $0.98
It costs about $0.98 per GH to operate. Divided by 10 for the chart above it is ~$0.10. If the green line drops below $0.10 you would be operating in the red.
Now lets look at a high cost low efficiency miner. $0.28 per kWh and 1.7 MH/W. Operating costs are 24*(0.28)/1.7 = $3.95 per GH.
On the chart above it would be drawing a horizontal line at ~$0.40. Everything below that was operating in the red.
BTW the $0.10 & 2.5MH/W is my farm so Bitcoins are selling at roughly 300% of my electrical costs. To be at breakeven price would need to fall to 1/3rd of today, difficulty rise to 300% of today or some combination.
Poll
