Assuming you pay for electricity/air conditioning and have a electricity rate of 5.5 cents per kilowatt hour, the next difficulty jump will make mining unprofitable!
At block 27,008
Rig=mobo/cpu, 2x 5870, 1x 5970
Wattage= 889
Second watt factor at 1.9
max Hashing power= 1390 mh/s -------> This is the max hashing rate I doubt most people can achieve this! In other words this is the limitation of current hardware available on the market.
Difficulty factor=495000
electricity cost @ 5.5 cents/kWh= $2.11 per day
.28 BTC a day or $2.09
kWh price calculator
http://www.citytrf.net/costs_calculator.htmyour wattage cost is calculated wrong for some reason, it should be 0.899 x 0.055 per kwh x 24 = $1.18668 a day on power (mining income still nearly 100% of power cost)
here is my stats :
2x 550w Coolermaster GX psu (binded/chained)
4x HD5850 @ 1100/1250 1.275v pulling full load 220watt per card so thats total 880watt
MSI 890FXA-GD70
AMD Sempron 145 underclocked from 2.8ghz to 1.4ghz @ ~30watt
Total full load as read from kill-a-watt is 1050watt for the whole system which equals 1.05 kwh @ 0.072c (avg out peak/offpeak to be conservative with calculations)
So I am hashing at 420mhash/s per card totalling 1680mhash/s for total power usage of 1.05 kwh comes down to the following net gain:
Revenue per time frame: 842.01 USD
Revenue minus power costs: 786.78 USD (this is taken on a monthly run at next difficulty, so if you want to be a prune half this if you want to make up for extra difficulty increases)
Hardware break even: 0 seconds (allready paid for)
Net profit first time frame: 786.78 USD (this is a gain not a loss, and a hefty one for just 4cards)
uh oh, I just showed you 1680mhash/s on a single mining rig.
If you arnt profitable, you didnt do your homework.