When we initially built this machine, one of the main focuses of blogging about building a massive crypto-currency mining machine was if and when we'd ever see a return on our investment. In the first blog, we stated what hardware we used. With the five 7970 cards, we spent almost $3000. And I'm fairly sure the two extra 290X snuck off and are in someone's gaming machine as I type. But those are fixed costs. We need to see how much power this thing is going to use and how much that power is going to cost us.
When using GPUs to mine for crypto-currency, your workload is pretty consistant making it easy to measure power usage with Corsair's Link software.
As we can see, we're pulling a fairly steady 1400W~1420W from the wall. We'll average that out to 1410W. If we have a look at the U.S. Energy Information Administration's website, we can see that we pay 13.01 cents per kWh. This is a bit higher than the national average, so if you're curious about how much electricity should be in your state, you can have a look at that website. If you're in Europe, the information can be found on the Eurostat page.
So, what is a kWh (kilowatt hour)? Essentially, it's the cost, per hour, to use 1000W (aka 1 kW) of power. Since we're using 1410W on average, and the cost of our power is $0.1301 per kWh, all we need to do is multiply 1410 by 0.1301 and then divide by 1000. This gives us a number of $0.183441. That's how much it costs us, per hour to run this PC.
From there, the math is pretty straight forward. We multiply by 24 to find out that our machine is costing us just over $4.40 per day to operate. Multiply that by 7 and we know that it's costing us almost $30.82 per week.
Of course, the power bill comes once a month, so let's take our daily cost, multiply that by 365 (days in the year) for $1606.94 per year. Divide that by 12 and we find we're paying $133.91 per month to run our massive crypto-currency mining machine.
Hmm... That's almost how much my electric bill is for my ENTIRE HOUSE! No doubt about it, it's not cheap to run five high-end graphics cards, full-tilt, 24/7. But we're keeping an eye on the coins we've mined. In the next installment, we're going to see if we've actually made any money, broken even, or completely throwing money away hand over fist!