Lowest Variable Cost to Mine BTC Assuming Non-Free Electricity

[EuSouBitcoin]

Assuming that you have to pay for electricity, what the lowest USD per BTC mining cost that you've seen? I want to exclude sunk costs like the cost of hardware. What's the best online calculator for calculating this cost?

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[DeathAndTaxes]

That is a very difficult equation to get a good estimate for.

Given no electrical cost and paying full cost of hardware then average ammortized cost of a bitcoin is:

(number of bitcoins generated in equipment lifespan)/(cost of equipment)

The issue is that you have two very difficult to predict variables
1) how long will the hardware last
2) what will the average difficulty be over that time period

Say you believe a new mining rig built today will last 3 years.  You can determine the lifetime shares the rig will produce.  Say you build a 4x5970 rig ~3.0GH/s for $2500.  Over 3 years with no downtime it will produce 66 million shares (2^32 hashes).  The problem is you need to know average difficulty to know how many bitcoins that translates into.

There simply isn't sufficient data to predict that with any reasonable level of accuracy.
You either need to take a wild guess or do so something simplistic like say I would earn X IF difficulty remains the same.

[fivebells]

If you're asking what's the best hash rate per joule of electricity you can get, it appears you get the best rate with the 5970 (see first table on this page.)

[EuSouBitcoin]

I know the difficulty can change. I was thinking more of given the current difficulty what is the cost of electricity to produce 1 BTC on the most efficient GPU.

[jjiimm_64]

the other guys are right, the 5970 is it. 

The best rig I have is getting 2905 Mhash/s pulling 1180 watts at the wall. (1250 if I use cgminer)

as follows:

msi gd70 mobo
4x5970s
2 750 seasonic psu
linux coin on thumbdrive
clocks  820/420
pic here:  https://picasaweb.google.com/112408294399222065988/October12011

[gnar1ta$]

clocks  820/420

Why so high on the memory?

[jjiimm_64]

aticonfig may report that you put it at 300, but it does not actually do it.  using cgminer you can see when the card reports the actual memory.

I used 420 and it worked..  tell you the truth I have not taken the time to see actually how low I can go, but it will not do 300

[gnar1ta$]

  tell you the truth I have not taken the time to see actually how low I can go, but it will not do 300

cgminer 2.0.6

Code:

root@miner:~# atitweak -s
1. ATI Radeon HD 5900 Series (:0.1)
    engine clock 860MHz, memory clock 150MHz, core voltage 1.05VDC, performance level 2, utilization 99%
    fan speed 69% (3940 RPM) (user-defined)
    temperature 72.5 C
2. ATI Radeon HD 5900 Series (:0.2)
    engine clock 840MHz, memory clock 150MHz, core voltage 1.05VDC, performance level 2, utilization 99%
    unable to get fan speed
    temperature 71.5 C

[jjiimm_64]

interesting...  did you flash the bios to get that?

[gnar1ta$]

nope...cgminer showed 150 as lowest so I set it at 150.

[jjiimm_64]

Nice.

I cannot use cgminer on all of my rigs until I upgrade my router to handle the extra requests...

also, it appears that I save about 75 watts using the old gui

[teukon]

the other guys are right, the 5970 is it. 

The best rig I have is getting 2905 Mhash/s pulling 1180 watts at the wall. (1250 if I use cgminer)

as follows:

msi gd70 mobo
4x5970s
2 750 seasonic psu
linux coin on thumbdrive
clocks  820/420
pic here:  https://picasaweb.google.com/112408294399222065988/October12011

Nice one!  The best I managed with my two 5850's was 732 MH/s pulling 302 W at the wall (only 2.44 MH/J to your 2.46MH/J).

These days my miner doubles as a Go bot so it's on 24/7 anyway.  If I decide to stop mining then all I will do is power down the cards (saving about 190 W) and so it's unlikely that they will become unprofitable to run, particularly with the current 45% income bonus of using merged mining.

[DeathAndTaxes]

Just curious how do you figure merged mining is a 45% bonus?

NMC are worth much less than bitcoins so wouldn't the bonus be much smaller?

[teukon]

Just curious how do you figure merged mining is a 45% bonus?

NMC are worth much less than bitcoins so wouldn't the bonus be much smaller?

They are worth much less but the difficulty is also much lower.  For every bitcoin you make with merged mining you will earn about 18 namecoins.  18 namecoins is worth almost half of a bitcoin at the current market rates.

[DeathAndTaxes]

I guess I need to read up on merged mining better.  How can one bitcoin block contain 18 namecoin blocks?  I thought it was 1:1.

[saethan]

My desktop gets me about 4.4 shares per minute pulling ~250w from the wall(it is not a dedicated mining rig, it has other parts that pull more power idle than would be necessary on a dedicated miner - and I have a few other services running that use a bit of cpu here and there).  Electricity is about $0.075 per additional kWh here.

Currently, each share gets me .000029597456 btc through ars.

(250w * 24hrs = 6 kWh) * $0.075/hr = $0.45 cost if that machine runs mining for a full day.

4.4 shares per min * 60 * 24 = 6336 shares per day = 6336 * .000029597456 = .1875 btc a day.

Current mtgox exchange rate puts that at $0.77 per day.

So, $0.32 a day profit.  Woo.  

Sure was a lot more profitable last week!  

A dedicated miner would involve adding 3 more cards, getting a cheaper processor, and downclocking the system RAM(and using a whole lot less RAM), and is much more profitable vs the wattage cost.

But to me it's helpful to know that the computer I use primarily for gaming is also more profitable to have hashing in its free time instead of doing nothing but running servers.  Though I don't actually sell btc at this point, I hoard them and also donate them to free services I use like minecraft SMP servers.  They're worth more to me than what people are willing to pay for them on mtgox right now.  

As an aside - the more merged mining gets used, the higher the difficulty namecoins will have, but is there actually much demand for namecoins for their intended purpose?

[teukon]

I guess I need to read up on merged mining better.  How can one bitcoin block contain 18 namecoin blocks?  I thought it was 1:1.

Approximation:  Most hashes are useless.  Some hashes are particularly small (difficulty 1) and can become shares.  Some hashes are really small (difficulty 94'035.90) and such a hash can be used to generate a Namecoin block (the same hash will also become a share).  Some hashes are extremely small (difficulty 1'689'575.83) and such a hash can be used to generate Bitcoin blocks (the same hash will be used to generate a Namecoin block and will become a share).  Just as one typically sees 1.7 million times as many shares as Bitcoin blocks, so too will one see about 18 times as many Namecoin blocks as Bitcoin blocks.

[rph]

I know you were probably asking about GPUs, but, for comparision:
An xc6slx150-2fgg484c FPGA uses about 5W at 96MH/s.

Electricity cost at $0.15/kWhr (socal) is about $0.54/month.
At $4/BTC it will produce $8.00/month in Bitcoins.

At current difficulty (1468195), it should remain operationally profitable down to around $0.27/BTC.

Of course - with that kind of collapse in the price - difficulty would also drop,
making it even more profitable.

-rph