Bitcoin Forum

Hi Miners,

There has been some discussion about the current costs associated with mining for bitcoins. Obviously it is dependent on a few variables but if we could come up with a ballpark figure, or a range, for the UScents per GHash/second at the current difficulty.

Take the most efficient card now available, AMD HD 5970, run it at most efficient clocking/power consumption, calculate the (GHash/s)/kiloWatt,
https://en.bitcoin.it/wiki/Mining_Hardware_Comparison
I suggest measure it directly for your total rig, i.e. include mobo, monitor if you use one, etc.

Multiply by your local kiloW.hr electricity rate and divide by Bitcoins per GHash/sec at current difficulty,
http://www.alloscomp.com/bitcoin/calculator.php

Estimate current UScents/ bitcoin. Add on top of that card amortisation (say 1 card last for 12 months on average). Call this gross expenditure.

Add on top 30% for sys admin and sundry overheads (more if you think necessary). Get final UScents per bitcoin, (or whatever your local currency units if you prefer.)

I'll do a spreadsheet if anybody wants it.

Here are some stats I just ran on my mining rig with two 5970's.  I have a "Kill-A-Watt" meter that measures the actual power consumption at the AC plug.

(Note, 5970 has two cores per card, so 4 cores)

Machine idle, booted up, no mining: 215 watts

Start 1 core mining: 315 W

Start 2 cores mining: 440 W

Start 3 cores mining: 560 W

Start 4 cores mining: 685 W

All of them are mining at stock specs.
After running a script that pushes them from 725 to 770 MHz and runs fans full speed: 740 W

For GPU only, it looks like about 120 watts per core, for 280 MHash/s, or 135 watts per core for 305 MHash/s.  Add 50W/core for mobo/CPU overhead (though one could fit more than 2 cards per board).

REAL cost of mining in watts for me: 305 MHash/s = 185W.  I pay about 9.5 cents per kWh, so in dollars...

$/Mhash = $0.095/kWh * h/3600s * 0.185kW / (305MHash/s)

= 0.095 / 3600 * 0.185 / 305 = $0.00000001601/MHash

$0.00001601/GHash

or 62461 GHash for $1

On average it takes about 4.2 GHash * difficulty to solve a block, Difficulty = 36460

So it takes me 153132 Ghash to solve a block, or $2.45 in power.

$2.45 / 50 BTC = 4.9 cents per BTC real power cost.

Wow your power is cheap. Here in germany I pay 0.20 euro cent kw/h.

Something seems wrong do you have 2 5970's?  5970's don't have 4 cores AFAIK.  Also it shouldn't be possible for a 5970 to use 500+ watts it can take about 150 watts from slot 150 from 8 pin pci-e and 150 from 6 pin I've heard 6 pin could use more without failing but would be out of spec.  That also doesn't take into account 5970 should be running at 50 or more watts at idle so it would be using about 600 watts at load something is wrong.

It says in his post that he has 2 5970s

Hehe I really need to learn to read sorry.