A PC costs $10 per month

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Newz2000
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A PC costs $10 per month

Post by Newz2000 » Wed Sep 20, 2006 1:37 pm

I have two servers in my house (plus an always on PC and two laptops :grin: ) I was wondering if I replaced these two noisy old servers with one, newer, lower power consumption model, how much I'd save.

One PC has two hard drives, 700MHz AMD k7, 256MB RAM and a 350w power supply, no monitor. Runs Myth TV, stays busy a lot.
Other has 1 hard drive, 350MHz P2, 192MB RAM, 400w power supply, no monitor. Does nightly backups, acts as a webserver, test environment for web apps and many other things.

These two servers don't have modern power management features like cpu speed stepping and etc.

I've seen it mentioned that a PC running is about equal to a 150w bulb.

I figure 150w x 24 hours x 30 days = 108kwh x $0.085 = $9.18. x 2 = $18.36 /mo.

I don't know an easy way to find out if 150w is realistic for my servers, but it shouldn't be hard to get my hands on a desktop computer that uses 100w and is much faster and has more storage space than my other two combined. (smaller too)

100w x 24 hours x 30 days x $0.085 = $6.12. Of course, it would take 2.5 or more years for the investiment to break even. But maybe if I factor in the money I save by using ccfl bulbs...

How's my math and my assumptions? Am I off the rocker?

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Chris Smith
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Post by Chris Smith » Wed Sep 20, 2006 2:31 pm

And then don’t pass up the wise old adage. ....

"Don’t put all your eggs in one basket"?

Safety in diversity.

How much is..... "piece of mind"?

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jwax
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Post by jwax » Wed Sep 20, 2006 4:59 pm

Big variable- PC power usage. Only way to tell is plug in a wattmeter and log consumption for a few typical days/weeks.

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Post by haklesup » Thu Sep 21, 2006 3:39 am

Dang, You got cheap electricity I pay over 11 cents/kWh for baseline (about the first 300kWh) and over 33 cents/per kWh for 300% over baseline. Since I use typically 280% to 350% baseline most months and I consider PC usage in the optional use class I would use the top price in my calculation.

Given the limits I consider baseline to cover cooking, heating and basic lighting. The next tiers covers TV and careless use of lighting and the third tier to cover optional use like an extra freezer, temporary house guests and that 2KVA steam generator in the shower. Even at its cheapest, I pay 50% more for power than you (8.5 cents/kWh). Furthermore, third tier pricing went up 3 times in the last 60 days in anticipation of winter when we all double our lighting usage not to mention heating (yes even a gas furnace has a fan)

I just trashed an old fridge that was using a whopping 10kWh per day and bought an energy star fridge that uses 1.8kWh per day. the first month the bill dropped by $50. It will take just over a year to pay for that new fridge, what a deal! Not only that but the power company paid me $35 to recycle the old fridge and they picked it up too.

I use the "Kill-A-Watt" meter to measure power usage and it only cost $25. Another worthy investment. It really put the nails in the coffin of that old fridge. Next I will replace a very old freezer that uses 5kWh/day with a chest freezer which are generally very efficient.

Depending on your motherboard, you can possibly underclock the CPU and lower the core voltage if the performance is not too critical. This could significantly reduce the power use as in CMOS devices, Supply current is a function of clock rate If you can lower V and I then P will obviously be reduced. For the Athelon, you may need to remove one of the chip caps from the top of the package (actaully they are jumpers) to set a new default speed.

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Post by stevech » Thu Sep 21, 2006 7:33 pm

I have a cheap DVM with AC amps.
I wired it so I can measure PC current consumption.

AMD 1800, one hard disk. 250W power supply. 30 watts. Doesn't vary.

The CRT monitor was 70 watts (on).
I no longer use CRT; LCD. Lots less.

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Post by Newz2000 » Thu Sep 21, 2006 8:50 pm

stevech wrote:I have a cheap DVM with AC amps.
I wired it so I can measure PC current consumption.

AMD 1800, one hard disk. 250W power supply. 30 watts. Doesn't vary.
Thanks for the info. That sets my mind at ease. For the pair that brings it down to $3.67 /mo.

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Post by ecerfoglio » Fri Sep 22, 2006 6:33 am

I have a cheap DVM with AC amps.
I wired it so I can measure PC current consumption. ..... 30 watts
There are two reasons that can make your measurements useless:

>>> Phase angle: AC Power is V x I x Cos Fi, where Fi is the phase angle between the voltage U and the current I.

>>> Waveform: cheap DMM's measure average values, not RMS. They are calibrated to read AC values only if you feed them a clean sinewave.

The PC's power suply's current is very far from a true sine wave, so the DMM's reading may be only a fraction of the RMS current.

To know how much power your appliances consume you need a wattmeter that reads true RMS values and phase angle.
E. Cerfoglio
Buenos Aires
Argentina

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Chris Smith
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Post by Chris Smith » Fri Sep 22, 2006 8:21 am

I think you will find they are close enough for argument, and not out by a mile.

I have both gages and reasonable DV meters, and I trust and use both for argument sake.

I doubt the values come anywhere near double, but rather, just a few percent difference for the cheaper stuff?

Id throw away any thing that bad.

This is single phase, not three, and tiny amounts of current.

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jwax
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Post by jwax » Fri Sep 22, 2006 12:55 pm

250 watt power supply consuming 30 watts. Always. That has got to be the most over-designed piece of consumer electronics on the planet.
Or measurement error.

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Chris Smith
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Post by Chris Smith » Fri Sep 22, 2006 1:18 pm

My 2400 MHZ Pentium with 480 watts of power supply runs at 10 cents per day, IF running @ 24 / 7. [$3.00 a month]

I don’t run heavy amps or sound.

Even with 7 hard drives when they are installed, they usually all don’t run at the same time and only draw a few watts each.

[6 watts / 3 watts each]

Newz2000
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Post by Newz2000 » Fri Sep 22, 2006 1:28 pm

jwax wrote:250 watt power supply consuming 30 watts. Always. That has got to be the most over-designed piece of consumer electronics on the planet.
Or measurement error.
I'm sure extra hard drives, high end video cards, killer sounds, DVD burners and multitudes of USB devices would consume more of that power.

Have you seen the USB missle launcher, the USB grill and the USB beverage chiller?

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Chris Smith
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Post by Chris Smith » Fri Sep 22, 2006 3:15 pm

My favorite is the USB coffee mug warmer?

JPKNHTP
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Post by JPKNHTP » Fri Sep 22, 2006 4:06 pm

-JPKNHTP
-God Bless

stevech
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Post by stevech » Fri Sep 22, 2006 8:09 pm

yeah, I know the DVM isn't taking into account the power factor for an inductive load.

But it's close enough.

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Externet
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Post by Externet » Fri Sep 22, 2006 8:23 pm

JPKNHTP :

It's simple; the author did hide a detail. The use of the new compact iridium-methane multiplier cells hidden in the base of the grill makes it possible, as they store about 3½ Kilowatts-hour, replenished by the paralleled USB feeds.
The prototype was designed March 31 last year by the George Foreman Grill Co. team.
Miguel

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