What is the average power consumption of a desktop computer?

[berniedd]

Just curious guys, but what is the average power consumption of a modern desktop computer nowadays? Let's say, a 3 GHz machine with one hard drive. Just the desktop, not including the monitor it connects to.

[c_hegge]

Re: What is the average power consumption of a desktop computer?

My guess would be maybe 150W or so.

[mariushm]

Re: What is the average power consumption of a desktop computer?

low end budget - high end

15w-40w : Motherboard

20w-40w cpu (when in desktop, idle)
50w-80w cpu (when playing games or doing very heavy processing) (add about 30-40w if it's overclocked)

If it's a Pentium 4 3ghz, that uses about 65 watts

3w - 7w : memory module

ssd drive: ~ 2w when idle, up to about 5w when writing
hdd: ~3w on idle , ~8w when used for the green/max 5900rpm drives, up to ~14w for the others
optical drive : ~ 3w when not idle, ~5w when spinning discs, ~8w if writing data to disc
fans/coolers : about 3-4w each

video cards...

agp cards are limited by the slot power which is about 35w - they used about 10w in desktop mode/2d/idle and probably up to 40w when playing games.

pci express video cards... this varies a lot but usually modern ones can use as low as 15-20w when in desktop mode or playing some movie and they can go up to about 220 watts when playing games or doing some opencl computing.

The basic rule is they can get up to 75w through a pci express x8 or x16 slot and they can get additional 75w through each 6 pin connector or 150w through each 8 pin connector, with a total limit of 300 watts defined by the ATX standard.

So a video card with no extra power connectors should never use more than 75w (though in practice there are some who go up to ~100 watts) and a card with just one six pin connector should not use more than 150 watts.

So your system would probably draw about 60-70w when you're playing Solitaire in Windows or watching a movie and probably about 130-160w when playing games (depending on what video card you have).

What you will actually draw from the socket is another story - that depends on the quality of your power supply.

If you have a cheap $20-30 400-600w power supply or an old computer, these power supplies have about 65-70% efficiency at such low loads and barely reach a 80-82% efficiency at around 60% of their rated power. So if this is the case, even though your parts draw 60-70w in idle, you'll pull about 90-100w from the wall.

Modern power supplies that are having the 80+ standard, will begin at about 78-82% efficiency at those low power draws. With such computers, if they stay on for 6-8 hours a day, it's worth spending 40-50$ on a 80+ Bronze power supply because you recover the money in about 10-16 months through lower power bills.


Real world example with power measured at the wall (90% efficiency power supply, A Seasonic X-650):

Intel Q6600 4x2.4 Ghz, 4 GB DDR2 (2x2gb), 3 hdd drives , dvd-rw , tv tuner on pci slot, 2x120mm fans, radeon 4850 512 MB

Uses about 160 watts when in Windows or watching movies, about 270 watts when playing games. Should be a bit less in idle but 4850 is not a particularly efficient video card, uses about 30-40w in idle compared to half on newer cards

[japlytic]

Re: What is the average power consumption of a desktop computer?

On one mini-ITX board running at full CPU load and a copy operation involving the optical drive resulted in a power consumption figure of 50W without factoring in the efficiency of the power supply.
I made this measurement when I was sizing up a 12V input ATX power supply (some have the 12V rail at the same voltage as the input).
The smallest 8-28V input ATX power supply I can find at a good price is a 160W unit, even though it is a bit of overkill.

[mariushm]

Re: What is the average power consumption of a desktop computer?

You can get smaller ones... a decent store (not the cheapest) for them is mini-itx.com :

http://www.mini-itx.com/store/?c=10

The ones with fixed 12v input usually don't filter the 12v output to the mainboard and other devices, only the 3.3v and 5v so the ripple depends on the 12v supply it receives.

That's why it's generally recommended to get the kind with flexible voltage input, because you'd be able to get a cheap 19v laptop and you'll have all three voltage outputs properly regulated.

You also have to be careful to power them with at least 12v, otherwise their specs are seriously downgraded - instead of 40-60w on 12v they'll barely be able to do half of that.


later edit: jonnyguru.com reviewed a few of these: http://www.jonnyguru.com/modules.php...Story&reid=207

[Hondaman]

Re: What is the average power consumption of a desktop computer?

I think it depends on what the "average" computer is.

I checked mine just the other night (finally got the Kill-A-Watt). My system is a couple of years old. Highlights:

Asus M2N-SLI (two IDE channels!)
Dual-core 64-bit Athlon (5400 = 2 cores @2700)
2 Gigs 800MHz RAM.
320 GB SATA HD
NVIDIA 7300GT video (28W maximum [256 RAM? 512?])
DVD/CD burner
Sound Blaster, speakers w/AC adapter
PCI wireless card
CPU fan and 2 case fans

The computer took 118 watts. All running at stock speeds.

Add 34 to 36 watts for the monitor (34 = still picture, 36 = Youtube video playing).

Just for fun, I added a SCSI card and two 18-gig 3.5" full-height 7200 RPM Cheetahs last weekend for a few minutes. Added 29 watts.

So for me, the answer is about 118W, but needing 35W more for the monitor. I perceive most people as using a faster, more power-hungry video card though.

[PCBONEZ]

Re: What is the average power consumption of a desktop computer?

Lacking a fancy video cards most PC's just don't use as much power as you'd think.

I tested the wife's machine a while back because the wall her desk is on only has one available socket so I figured I should check the loading. Never tested the other PC's because the loading on those sockets wasn't in question.

Abit IP35-E
C2D E4500
4GB DDR2-800
Promise RAID card [at the time, now it's 3Ware]
3x 500GB WD 7200RPM [2x mirrored + hot spare]
NVIDIA 7300GS
2x Optical
DVICO Fusion HDTV-5 Gold TV Tuner
80+ PSU [Earthwatts]

Had to push it to get it to 120 watts on the Kill-A-Watt meter.
'Normal' active use it was right around 105 watts.
Spent a lot of time at <100 watts which surprised me.

Now you know how those Dell mini-machines can get away with 180-210 watt PSU's.
.

[brethin]

Re: What is the average power consumption of a desktop computer?

It depends on the computer. Newer standard destops sold now require much less power than a system sold several years ago and are much faster. The biggest change is the power requirements have changed in new systems so the PSU's have changed. A 450w PSU designed for a P3/P4 or older AMD will have much higher output on the 3.3v and 5v rails than a PSU sold today for a I3/I5/I7/I9 or newer AMD cpu. You would have to be specific with the hardware if your looking for a answer for a specific system. If i had to guess the adverage on a new standard (latest hardware) system I would say around 170w.

[#2pencil]

Re: What is the average power consumption of a desktop computer?

HI,Newbie here, I have been trying to find out how much power my PC uses and the info in
these posts tell me that even with a older PC i still have a little wiggle room left.
I have a DELL E521,WINXP,SP3,2GB RAM,PSU is supposed to be 305watts.

[severach]

Re: What is the average power consumption of a desktop computer?

The Kill-A-Watt meter will report the power consumption and allow you to test power abatement strategies now that summer is coming to the northern hemisphere. OS & RAM have no effect on power consumption. The E521 won't have an 80Plus power supply. I'd say 95W if you got the cheepie video card and 75W if you didn't.

The low end of power consumption is about 65W unless you're like me and purpose build systems for ultra low power consumption. I like my 17W idle uATX servers, just enough to keep the room warm in the winter and getting rid of the 70W idle servers reduced the temp from "oven" to "sauna" in the summer.

Most Dell supplies are well known to provide all of their rated power and a bit more. You're going to need a good size video card before the Dell 305 runs out of power.