I read in a few places that running BOINC can cause you to get a pretty big electric bill... I have a few friends who run it pretty much 24/7 and the opinions I got from them were rather mixed.

I did a little math to try and figure it out for myself, here's what I came up with (just as an example):

200W computer, electricity price 15 cents per kWh.
costPerYear = ((Watts*60*60*24)/(1000*60*60*24))*price*365

If it's on all year, this gives $11 total electricity cost.

Is there something I'm missing here? I had the impression that some people were losing huge amounts of money to this, on the order of $1 per day per CPU. How could that be the case?

EDIT: Please, if I'm wrong, let me know.

Depends on the CPU you have in there, the amount of cores, how many GPUs you run, how much memory, how much cooling and what kind, etc. etc.

There are people with just one computer, there are those with whole farms (20 and more). A typical computer with GPU that does work has a 550Watt PSU.

Now, there's a flaw in your calculations.
You say it's ((Watts*60*60*24)/(1000*60*60*24))*price*365, but it's really ((Watts / 1000) * 24) * price * 365 - see what I did there? You run in kiloWatt hour, so all you have to do is calculate KiloWatt (Watt divided by 1000) and multiply with 24 to get to the day amount in kWh.

You don't run kiloWatt per second per minute per hour.

I'd say, check against http://www.citytrf.net/costs_calculator.htm, which does it better.

My PC runs with a 550W PSU, 1 ATI GPU doing OpenCL work, 1 Intel i5-2500K CPU (4 cores), runs full bore (high load) for 10 hours a day and 24 hours in the weekend at cheaper rates, at 10 cents an hour. So (outside of holidays) these'll cost me at maximum ((550/1000)*10*0.10*261) + ((550/1000)*24*0.10*104) = €143.55 + €137.28 = €280.83 per year.

Added to that the running cost of leaving a computer on for 24 hours... I put mine to hibernate these days. Or turn it off during the day. The rest of the time the computer is either off or runs in low power mode.

Last year I managed to get 700 euros back from my energy bill, while the years before that I had to pay 1500 extra. After the last 1500 extra, I had a dual meter installed, one that runs 9pm-7am at a cheaper rate of ~ 10 cents (against 13 cents during day hours), set only my own computer to run BOINC and only during those hours. It also helps to invest in newer equipment. I ran a couple of P4s and a single core AMD before, but they're all upgraded now. The i3, i5 and i7 all go into a low power mode when they're not under high load. This helps a lot for energy conversing.

---

Thanks for pointing out my math error there. Now it all makes a lot more sense...

Actually I think you pretty much answered my entire question, and then some. Thanks a lot!

OK, so here's a new question:

How much power does the average computer use? I know this is much too general, every computer is different, etc. But in general, what is the average wattage of PC's VS laptops, idle VS full load.

I did try doing some research on my own, but I got bogged down in the details... I'm just looking for ballpark numbers here.

Best thing to do is use a Power Supply Calculator. It's what we, who build our own systems, do.

---

I'm not trying to build my own system... couldn't you just give me a ballpark estimate, for the average computer?

No, not really. It really depends on the motherboard+CPU you have in there and the amount of GPUs.

If it were pre-GPU era, I'd say ave 550W. But now I am not so sure.

---

I put a KilloWatt meter on my main i7-950 system to test things out... With everything overclocked to the hilt, it pulls about 735 watts under full load crunching. 4.25GHz CPU and 950MHz GPU's...

Of course, it isn't your average system either... has a dozen fans and water pump and all that... has 1200W PSU...

http://i.imgur.com/wzbpP.jpg
http://i.imgur.com/6pajD.jpg

Other boxes pull between 450 and 700 under full load... so all depends... Cost me about $160/month to run them...

8-)

Wow that's a badass system you've got there! How many GFlops/sec does that thing do? Did I mention it looks badass?