Quote from: markm on July 18, 2013, 12:33:19 AM

Quote from: thef on July 18, 2013, 12:25:09 AM

The price would have to go a lot lower for mining on CPUs to not be able to pay for electricity. A CPU might use at most 2.5 KWH per day which would cost around $0.30 per day to run. At a price of .007 BTC/XPM and 12 XPM per block, it would be profitable to mine even if you only received one block every 20 days.

Maybe, if you only count the extra CPU-usage, that is, if you already have the motherboard and internet connection and whatever else you leave attached (disk? mouse? keyboard? whatever) running 24/7 anyway.

However a lot of "normal people" seem not to normally leave their machines on 24/7, so for them it might be more like "a normal PC uses 200 watts, which is one kilowatt-hour per five hours, which comes close to five kilowatt-hours per day, assuming your machine really does not go over 200 watts at the wall when cranking all its cores full blast".

I used to figure turning on a machine cost about $30/month at $0.14 to $0.15 per kilowatt-hour until I got a kill-a-watt meter and learned my box with a 5870 in it was eating 240 to 250 watts before even firing up a miner to mine with that GPU, and more like 340 to (once warmed up) 370 with it mining. Admittedly that was before taking it in to have massive amounts of dust removed from inside and new thermal paste for its CPU heatsink so its CPU would not keep throttling from overheating and its fan control wouldn't keep blasting the fans as loud as they would go.

So when its a matter of whether to plug in or turn on yet another of the machines the air conditioner is trying to make you willing to put up with the noise and heat of, I think your "at most 2.5 kwh/day" is somewhat optimistic.

I have a 12000 BTU air conditioner outside in the minivan waiting for the guy who is making us new windows to come by and install because the 8700 BTU unit currently in my current window cannot handle the heat if I turn on (in addition to what I have on 24/7 already) the four Dell Optiplex 755 boxes. So depending on the season/weather even just the turning on another computer estimate is a little low...

(Not to mention, oh heck with it lets mention it, that I also had to provide an air conditioner (I got a 6000 BTU) at the other end of the apartment so others here don't get too overheated.)

-MarkM-

You're right. I was thinking of just turning on a cpu in a mining rig, but it would cost more for air conditioning and turning on machines that would otherwise be off. However, I believe most people leave their computers on all day, so the extra cost would only come from the CPU. I guess in a worst case scenario where someone turns on a computer that would otherwise be off just to mine would use an extra 200 watts. I actually consider this a high number since I've read video card reviews where the entire system used less than 100 watts at the wall at idle. Assuming air conditioning would use another 200 watts, power consumption would be 10 KWH per day. In the most unfavorable circumstances, people are still going to mine even if they can only get one block every few days.