How much will my old systems ding my power bill???

[jazzman42379]

Hi All,

Through the last couple years working for my school's IT Center, I've acquired a number of less-than-modern PCs that I've used for a number of things. Now that I don't live on campus anymore, and pay for my own power bill, I'm thinking maybe using all these old PCs isn't such a good idea.

For example, I have the following 5 systems running pretty much 24/7:
- TBird 1400 w/cheapo 300W PSU
- AthlonXP 2000+ w/cheapo 350W PSU
- P3-450 w/old 250W PSU
- P2-333 w/old 235W PSU
- AMD K62 w/old 235W PSU

My power bill shows electric usage from the last year, and the power usage is more than doubled! (ex. last July = 272KWh, this July, 731KWh)

So I'm wondering what effect all these systems is having on my power bill. Is it simply the fact that there's 5 systems always running? (I turn the monitors off when not using them, not just power save) Or could the old/cheapo power supplies be the culprit? Or are these old processors sucking more juice? None of the systems have anything extreme in them as far as cooling, and none are overclocked.

Another question, for the next round of upgrades...what would be the most power efficient quality in a system? The processor, power supply, hdd, etc? I've noticed that the little Shuttle XPCs only have 200W PSUs, but the reviews on NewEgg look like that's enough to drive the high-end P4s and powerful AGP cards. Would something like this save me power? Or does it matter much? Or would going with minimal Celeron systems and new, efficient PSUs help?

Thanks in advance...
Jazzman

 

[EeyoreX]

I don't know that much of anything will help. Save for not running 5 PCs 24/7. I tend to think that even 5 slightly more efficient systems will draw a bunch of power. I seriously doubt there would be a significant dropoff in power usage. What do you use 5 PCs for 24/7? If they are a bunch of file servers or something it would be a much bigger savings to consolidate into one system in addition to your main one. If you have 5 people using 5 different PCs 24/7 that's different, but it doesn't sound like that to me.

\Dan

 

[vegetation]

Your systems are not that old, so the power usage will be higher than you might think. Each one probably around 90 watts of power idling with the hard drive on. That may not seem like much, but 90*5 = 450 watts, that's about the power level of a small room air conditioner. Leaving it on 24/7 will definitely make your power bill higher. How much so varies on where you live. What are you running that requires 5 low end systems to be on all the time?

 

[mechBgon]

A person recently reported that his AMD system is pulling about 160W at the wall socket with the monitor off, using a device that's made to test actual power draw. Let's start with the assumption that all of them drew that much power, for simplicity.

So...

160 watts x 0.001 killowat per watt x 24 hours x 365 days/year = 1400 kW-h/year (per system)

Let's say electricity costs 6¢ per kW-hour where you live.

$0.06 x 1400 = $84 per year (per system)

5 x $84 = $420 per year total


Addendum: Now, seeing that you live in Montana, during the months when you heat the house, this is the equivalent of electric heat, so it's not exacty wasted. However, whenever your air conditioning is on, you pay about three-and-a-half times for this electricity... once for the heat generated, and 2.5 times more to pump the heat outside via the AC.

 

[Mark R]

The older systems use substantially less power than new ones like P4 and athlon.

The other important point is what software is running - if you are running Linux or Windows NT/2K/XP then idle consumption is considerably less than power use under load (the same is true under Win 95/98/me but to less of an extent). If they are running SETI@Home or another distributed computing project, then this will seriously increase their power consumption and subsequent energy cost.

I'll ignore monitors, as I can't estimate their use - due to standby modes, etc.

I'm going to try some estimates jsut off the top of my head (though they are based on a few measurements that I have made).

TBird 1400 - 100W idle (130W load)
XP 2000 - 120W idle (150W load)
P3-450 - 70W idle (80W load)
P2-333 - 60W idle (70W load)
K62 - 50W idle (60W load)

So potentially your power consumption is 400W if they are left idle or 490W if running working software.

Power costs vary but I'll assume $0.06/kWh - this works out at approx $18/month (idle) to $22/month (load).

 

[jazzman42379]

Thanks for the tips everyone....

I know 5 systems 24/7 is a bit excessive (hence this post)...but in working towards MCSE/MCSA, I work with Windows OSes a lot, and use my home network as a lab environment. So the 5 PCs include 2 domain controllers/DNS servers, 1 firewall, 1 public web server/mail server, and the 5th is just my desktop PC I use on a normal basis.

Some of you pointed out some rough extimates of power usage. Is there a way to figure this out? Would a voltmeter be able to figure power usage, or is that too much for a typical volt meter.

Also, I saw a post where someone responded saying that regardless of what size your power supply is, it only produces what is needed. So the size of the power supply doesn't matter as much as what's in it. Does this sound accurate?

Thanks again, everyone,
Jazzman

 

[Barnaby W. Füi]

Maybe look into vmware, you can run 10 computers inside of one, and play with networking and everything. You'll save a tree, too.

Also, I saw a post where someone responded saying that regardless of what size your power supply is, it only produces what is needed. So the size of the power supply doesn't matter as much as what's in it. Does this sound accurate?

Yes, that is correct. However, some power supplies are slightly more efficient than others.

 

[grant2]

Originally posted by: BingBongWongFooey
Maybe look into vmware, you can run 10 computers inside of one, and play with networking and everything. You'll save a tree, too.

I didn't know/consider that VMware could have all your virtual computers on the same network... that would totally rock for developing client/server applications.

 

[0roo0roo]

if they are doing nothing most of the time, even with power saving they'll probably use over 100 watts is my guess. thats gonna eat into your power bill. why do such a thing?

 

[zephyrprime]

You can bet that all those extra computers are driving your electric bill through the roof.

Each system consumes about ~130watts idle so...

0.13KW*24Hours*5*30days/month*1month =468KW/Hrs per month

If you want to lower power consumption, sell all your extra computers and get a single P4 system that will meet your needs. P4's use the halt on idle instruction so they have lower power consumption while idle.

 

[jazzman42379]

zephyrprime: Is the halt on idle feature of the P4 something you have to activate or is it automatic? And what defines idle? These systems are mostly supporting servers running AD, DNS, WINS, etc...so they aren't heavily used at all.

Would using little VIA EPIA systems help out? Or would those too add up to a lot?

Thanks everyone!
John

 

[HalfCrazy]

I have three desktop systems on a KVM box. The most computers I have running at one giving time. Is only two computers since I like to play single player games. Then able to bring up some game hints about the game on the other system.

 

[zephyrprime]

zephyrprime: Is the halt on idle feature of the P4 something you have to activate or is it automatic? And what defines idle? These systems are mostly supporting servers running AD, DNS, WINS, etc...so they aren't heavily used at all.

It's automatic on Win NT & Linux based OS's and but it's not on Win9x. Although you can get CPUIdle or something like that to use it. But AMD processors don't exactly support HALT in the conventient way so you much use CPU Idle if you want to AMD's version of HALT. The little server daemons you mention are very un-processor intensive so you can bet that you CPU's are actually idle the vast majority of the time. Use Windows NT's task mananger to see how idle you computers are. Open tm and add the "CPU Time" column (this is done using the menu).

Would using little VIA EPIA systems help out? Or would those too add up to a lot?

Yes but the big thing is just to have fewer computers.