Computer electricity consumption

[plastick]

okay i hope this is the right friggin forum for this..

I was wondering if the average computer consumes more electricity when left on all the time as apposed to when its being turned on and off after its done being used.

Im asking because Im moving to an apartment where i have to pay for my electricity so i want the bill to be cheap. Plus its good common knowledge..

I have an athlon 64 bit cpu vnf3 mobo with a gforce 4 video card and i usually use it for internet and word processing and photoshopping and play games like starcraft (So thats what i demand from my pc).

any info?

 

[DrPizza]

How long is it going to be off for?
But, yeah, it consumes less electricity when it's off. Maybe a better question is "how much will I save each month by turning it off for 8 hours a day?"

 

[plastick]

lol

well what i am asking.. there is that thought out there about how it takes more energy to boot up your computer than to just leave it on. You know what i am saying? or is that a myth?

obviously leaving it on for a month will cost electricity... but i heard that it takes a lot of juice to start up a pc.. so i should just leave it on, unless i leave for the weekend or something.. this is a general question..

 

[Matthias99]

Originally posted by: plastick
lol

well what i am asking.. there is that thought out there about how it takes more energy to boot up your computer than to just leave it on. You know what i am saying? or is that a myth?

obviously leaving it on for a month will cost electricity... but i heard that it takes a lot of juice to start up a pc.. so i should just leave it on, unless i leave for the weekend or something.. this is a general question..

The amount of extra power used at startup is trivial compared to how much it uses while on for a few hours.

There have been a number of power consumption articles and reviews done on the web... I'm sure some searching would turn up useful numbers.

Without a monitor, most systems would use under 100W at idle (from the wall; remember you have to take the PSU's efficiency into account). And way less if you put them into a power-saving 'sleep' mode.

 

[Mark R]

Yes, there is a small surge when you switch on (probably an extra 10 Watts for about 5 seconds while the hard drives start up). This 'surge' is so small it should be igored.

If you want to minimize power consumption you should make sure that the appropriate CPU drivers are installed (e.g. Athlon 64 Cool and Quiet) - these will 'underclock' and 'undervolt' the CPU when idle saving electricity and producing less heat.

Most importantly though, is to get rid of animated screen savers and to cofigure the screen saver to switch off the monitor after 5-10 minutes of non-use. And, if you can configure your system to standby properly (unfortunately, lots of substandard peripherals - like Lexmark printers - will crash your system if you let it go into standby), you should enable this.

In standby mode, power consumption is very low indeed - and it should only take a 5-10 second delay for it to wake up again.

 

[plastick]

cool

 

[modedepe]

Originally posted by: plastick
lol

well what i am asking.. there is that thought out there about how it takes more energy to boot up your computer than to just leave it on. You know what i am saying? or is that a myth?

obviously leaving it on for a month will cost electricity... but i heard that it takes a lot of juice to start up a pc.. so i should just leave it on, unless i leave for the weekend or something.. this is a general question..

I've heard lots of people say that it's better to leave on, but never for the argument that it uses an excessive amount of power (usually people argue that the transient voltages are bad for the system).

As others said the extra power used when starting up is next to nothing. If you want your bill as low as possible, turn it off. That said, as long as you turn off your monitor, it isn't that much of an increase. I leave mine on 24/7, but if the increase was substantional, I would turn it off.

 

[Bassyhead]

I leave my system on all the time. If you want to conserve power, have your system suspend to RAM or hard disk, you'll only use a few watts in this mode with your monitor and all peripherals off.

 

[vegetation]

A typical one-drive, integrated video, P4-2ghz machine consumes approximately 50-70 watts unloaded (based on my experiences with a Kill-a-watt meter), not including monitor. Use that as a baseline and figure out your electric consumption. Running 24 hours a day certainly puts a huge dent in your bill compared to just flicking the switch off.

Aside from that, if you want a low powered system, seriously look into running a laptop as your primary, if only, machine in the house. A typical pentium-m system will use 25 watts or less at idle, with the screen powered ON.

 

[jagec]

Originally posted by: plastick
I have an athlon 64 bit cpu vnf3 mobo with a gforce 4 video card and i usually use it for internet and word processing and photoshopping and play games like starcraft (So thats what i demand from my pc).

You could save money by running a 300MHz Celeron with onboard video, if that's all you demand from your PC.

 

[usernamemax20charact]

Sleep/Standby mode is the answer...

 

[uOpt]

I have a powermeter.

Generelly both my Northwood P4 and my Newcastle AMD64 take avout 120 watts out of the line when idle. When loaded with lots of harddrives and cards they end up in the 150-160 area. Loaded CPU and graphics cards takes the AMD64 well above 200 watts.

The Athlon XP with via chipset I had was much worse, actually, AMD 64 made great progress. Obviously Prescott CPUs are not for people with powermeters.

My 68800 Ultra actually takes up some decent amount when idle, forgot what it was, 30 watts? Must more than my 5900XT. I'll try an underclock BIOS for 2D, maybe.

The Seasoniq PSUs I have feed the same computer with 10% less (they pay for themself in a PC running for a few years constantly).

 

[Calin]

I know that while heating, a incandescent bulb consumes more power than when running at its normal temperature. Should I let the lights on all the time or should I just turn it off when not needed?

 

[MobiusPizza]

lol

yeah I was a bit amused by the question initially
Turning off computer = 0 power consumption.
Given that the computer didn't explode when it start up it should not have used up more power than turning it on all time.

Also note that power is defined as energy transger per second. Turning computer on means you consume 100J of energy per second, and 0.1kWh for 1 hour. Starting computer only takes seconds. Even if it uses 1000W to power up, it only translate to 0.00001kwh

 

[Jeff7]

Originally posted by: jagec

Originally posted by: plastick
I have an athlon 64 bit cpu vnf3 mobo with a gforce 4 video card and i usually use it for internet and word processing and photoshopping and play games like starcraft (So thats what i demand from my pc).

You could save money by running a 300MHz Celeron with onboard video, if that's all you demand from your PC.

Heck with that, build a mini-ITX system. VERY low power consumption.

Originally posted by: AnnihilatorX
lol

yeah I was a bit amused by the question initially
Turning off computer = 0 power consumption.
Given that the computer didn't explode when it start up it should not have used up more power than turning it on all time.

Also note that power is defined as energy transger per second. Turning computer on means you consume 100J of energy per second, and 0.1kWh for 1 hour. Starting computer only takes seconds. Even if it uses 1000W to power up, it only translate to 0.00001kwh

Actually, it'll still use some power. Like all too many devices these days, ATX power supplies are only off if you use the hard switch on the back to literally cut power to the supply. Other than that, it's in a soft-off state, still using power. Heck, my speakers use a few watts when they are "off." Rather annoying, really. Maybe I should get a power strip or something with lots of switches, except that I'm on a UPS, so it would need to lack surge suppression capabilitiees.

 

[uOpt]

Originally posted by: AnnihilatorX
Turning off computer = 0 power consumption.

Not quite true, most computers with ATX PSUs still draw about 7 watts when the computer is off, where off = turned off via ATX (not sleeping/suspended). You have to cut it from power to prevent that.

 

[vegetation]

Originally posted by: Calin
I know that while heating, a incandescent bulb consumes more power than when running at its normal temperature. Should I let the lights on all the time or should I just turn it off when not needed?

Always turn lights off if issues such as safety, security, or mood are not issues at hand in the area to be lit. The warm up period is not worth considering. Also, switch to compact fluorescent lights to really save on electric bill. The ROI on CF's are way up there.

 

[uOpt]

BTW, here's the mesurements from my latest fiddling and PSU change


Power usage in watts idle/busy (CPU+GPU busy). The machine is a
socket 754 Newcastle AMD64 3400+ (2.4 GHz, 512 KB cache), NForce 250
GB chipset, assorted PCI cards (SCSI, ethernet, sound, TV).

2x disks Sata + 1x disk PATA, 5x optical drive (idle)
- start: 6800 ultra + zalman PSU 175/301
- rip out PCI cards, all opticals, only 1x PATA HD 129/251
- switch to Seasonic PSU 117/225
- rip out 6800 Ultra, put in 5900XT 98/186

(less than 100 Watts for a killer machine with AMD64 3400+ and 5900
XT, not bad I say).

Reassemble computer:
- 6800 Ultra, 1x PATA disk, PCI sound 128
- +PCI TV, Ethernet, SCSI 130
- + 6x optical (muhahaha!) 156
- + 2x SATA HD 181
- - 5x optical (keep only ATA DVD-R) 161
- opticals back in 181
- + 2x Fan Panaflow 80mm low-speed chinese 182
- reduce opticals to ATA DVD-R + 3x SCSI CD 175

 

[bluestrobe]

Originally posted by: vegetation

Originally posted by: Calin
I know that while heating, a incandescent bulb consumes more power than when running at its normal temperature. Should I let the lights on all the time or should I just turn it off when not needed?

Also, switch to compact fluorescent lights to really save on electric bill. The ROI on CF's are way up there.

I almost lost my house due to 3 of those lights. Don't use them unless you have a constant, steady voltage and you can check on them every day. Caught one dripping melting plastic onto the carpet just seconds from turning into a flame.

 

[pm]

I have a "La Crosse Cost Control" Power Monitor. Got it from my mom for Christmas.

With my 3.2GHz Pentium 4 system, and a 22" NEC FP1355 CRT, it is currently reading 248W and I have World of Warcraft and iTunes running in the background. With the monitor off it's 162W. Idling it's usually around 100W.

Local electricity is roughly $0.06 per kW hour (yes, local electricity is cheap). So, at 248W - which I'll round up to 250W, that's $0.06 * 0.25kW = $0.015 per hour.

Surge current when a computer turns on is not worth considering... the concern is over whether it hurts the computer. Still given MTBF rates and considering that when it's off, it's free... I'd turn it off when not in use.

 

[jagec]

Originally posted by: MartinCracauer
The Seasoniq PSUs I have feed the same computer with 10% less (they pay for themself in a PC running for a few years constantly).

Are you sure that power meter is measuring true watts and not VA? Because that could just be the power factor correction that you're seeing, and that saves you exactly $0 on your power bill.

 

[Calin]

There are special multimeters to measure reactive power. The usual ones you can find measure only active power (or W)

 

[uOpt]

Well, I'd have to look it up when I get home, I don't remember the brand of my powermeter off-hand.

But the Seasonic PSUs have been tested in reviews, e.g. on silentpcreview.com, to be 10% more efficient than anybody else, so I think this is for real. Seasonic also advertises with this.

It turns out that the Zalman 400B is actually my least efficient PSU, at least according to my powermeter. It's great otherwise, though.

 

[Jeff7]

Originally posted by: bluestrobe

Originally posted by: vegetation

Originally posted by: Calin
I know that while heating, a incandescent bulb consumes more power than when running at its normal temperature. Should I let the lights on all the time or should I just turn it off when not needed?

Also, switch to compact fluorescent lights to really save on electric bill. The ROI on CF's are way up there.

I almost lost my house due to 3 of those lights. Don't use them unless you have a constant, steady voltage and you can check on them every day. Caught one dripping melting plastic onto the carpet just seconds from turning into a flame.

From CFL's? Did you notify the manufacturer about it? Hopefully they'll be more than eager to help you out, as it'd be VERY costly for them in terms of legal fees and public relations if their products were found to be the cause of a house fire.



As for Seasonics and efficiency, I got these power numbers, which have been adjusted for the power factor, as measured by a Kill-A-Watt:

Antec Truepower 430W: 208.21 Watts
Seasonic 460AGX: 190.46 Watts

That's for the exact same system, under load both times courtesy of Prime95. 8.5% reduction in power consumption.

 

[Mark R]

The latest power supplies with Active PFC are considerably more efficient than older non-PFC, or passive PFC supplies. Efficiencies for a good quality, high efficiency supply are around about 80-85%. Non-PFC have traditionally been around 70-75%.

The Antec Truepower is one of the older active PFC designs - basically the active PFC was bolted on as an afterthought, and it makes no difference to efficiency (actually, it could even make it worse).

An active PFC circuit actually has a few side effects that can be utilised to improve efficiency and power quality - but you do have to redesign the PSU to take advantage of them. Enermax and Seasonic are two OEMS that have redesiged their supplies in this way.