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 Post subject: PFC suggestions
PostPosted: Thu Apr 17, 2003 6:10 am 
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Joined: Wed Apr 16, 2003 1:20 pm
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Location: Madison, WI USA
Are active PFCs a common feature in new PSU's? I was truly interested in the proSilence PSU until I saw the Verax review which discussed PFCs, and being interested in doing my part to help save the planet, steered away from that direction. I'm really leaning towards one of those 14dba ExoticPC PSUs.

A two parter; given the large debate of 300W~400WPSU's, does anyone think it's worthwhile to go 400W in terms of future computer needs? My CPU now is really low powered (600 Duron, low end vid card, a couple disks), but I can see myself upgrading in the next two years, and keeping whatever PSU I buy.

-Michael


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 Post subject:
PostPosted: Thu Apr 17, 2003 6:26 am 
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First welcome.

Quote:
Are active PFCs a common feature in new PSU's?
In Europe (EC) certainly: they were hard to find a year ago but now most/all psus have it. It you are not in Europe I have no opinion.

Quote:
does anyone think it's worthwhile to go 400W in terms of future computer needs?
No - unless you have an immediate need my opinion is wait. If you buy a 400W now trying to 'future proof', by the time you need the 400W you may discover your 'old' psu doesnt have the "whatever it is you need connector". Certainly if you are buying a psu now, and all else is equal, then take a 400W in preference to 300W. Except bearing in mind that the psu is around 65-70% efficient means (assuming 65%) a 300W psu has to be fanned to clear 165W of heat, a 400W has to be fanned to clear 215W. Which means an equivalent 400W design needs a lot more airflow (= noise) and you are at the mercy of the temp sensing fan design how much of that noise remains when you are only using a fraction of the peak power output.

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 Post subject: Re: PFC suggestions
PostPosted: Thu Apr 17, 2003 7:31 am 
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Location: Cambridgeshire, England
mdhare wrote:
Are active PFCs a common feature in new PSU's? -snip- and being interested in doing my part to help save the planet, steered away from that direction.


I think you might be a bit confused here.
The active PFC function they are refering to has nothing to do with Flouro-Carbons. :P
They are refering to "Active Power Factor Control" that actively regulates the voltage fed to the motherboard based on usage.

Hope this clarifies.

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 Post subject:
PostPosted: Thu Apr 17, 2003 7:40 am 
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I don't think he was referring to fluorocarbons. Quote from the Verax review:

"[PFC] it is very relevant to real electricity consumption and energy conservation."

So, by all means get an active PFC unit.

You'll not only save on energy, but also your power company will be happier the more people use APFC units.

And mother earth will thank you as well :)

regards,
Halcyon


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 Post subject:
PostPosted: Thu Apr 17, 2003 10:21 am 
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How does PFC reduce power needs -- anywhere in the power grid? I thought that all it did was reduce the amp demand on the power company but didn't really waste any power.

The passive PFC coil in my 300W Sparkle measures 2 ohms resistance. So doesn't that mean it's going to waste roughly 25 watts at full load?


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 Post subject:
PostPosted: Thu Apr 17, 2003 1:05 pm 
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as another poster stated in another thread, you power consumption isn't lowered by an active pfc, rather your Volt-Amps are. However, at least in the U.S., the power company only charges for effective power or Watts. On the other hand UPS' work off of VAs so if you're using one the effective time that your system(s) can run off battery will be increased with an active pfc. Large companies have PF thresholds that they are penalized for not complying with and/or are rewarded for complying with so that's a consideration too. However, for the average home user the only thing that effects power consumption is the PSU efficiency.


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 Post subject:
PostPosted: Thu Apr 17, 2003 11:41 pm 
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I'm not an expert on this, but two things:

1) If it doesn't show on your electricity bill, it doesn't mean that energy is not lost. PF problems cause a lot of extra work and power transmission loss to electricity companies, hence correcting PF does save energy (companies may just may not be able to bill you for it, or it may not be billing efficient until you consume a certain amount of energy). Also, improved PF can lead to heat reduction in some electrical equipment.

Resources:
http://www.powerstudies.com/content/res ... Factor.pdf
http://www.essex-power.com/commercial/power_factor.cfm


2) If one wants to think about environment, one can also weigh the effects of energy saved (via properly done PFC) against the additional impact of buying more hardware. On the short term, buying a new PSU is more damaging to the environment than the energy saved. However, on the long term the electricity saving start to balance the penalty of producing/transporting/selling new hardware. The impact of the latter can be measured in MIPS (material Input Per Service unit) and can be difficult to pin down often.

Resources:
http://www.ife.uni-freiburg.de/Homepage ... andito.pdf


Last edited by halcyon on Mon Apr 21, 2003 10:29 pm, edited 1 time in total.

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 Post subject:
PostPosted: Fri Apr 18, 2003 1:51 am 
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Location: Antwerpen Belgium
Power companies charge for VA, so PFC will reduce your bill.

The power companie measures your current, not power, they then multiply the current by voltage and express the result as power.
If your PFC is 1 then the power figure is true, but otherwise the true power is less than your bill says.


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 Post subject:
PostPosted: Fri Apr 18, 2003 7:01 am 
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Joined: Wed Apr 16, 2003 1:20 pm
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Location: Madison, WI USA
I just wanted to say thanks for all the information and links regarding this subject. It's been very helpful.

In all I ditched the idea of going for the prosilence. Between the cost, extra power consumption, and having a hard drive (barracuda V) in the system anyway, figured the perceived DBA difference would be essentially nothing.


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 Post subject:
PostPosted: Fri Apr 18, 2003 5:03 pm 
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Don't power companies use wattmeters, which compensate for PF?


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 Post subject:
PostPosted: Fri Apr 18, 2003 5:04 pm 
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Joined: Tue Dec 03, 2002 11:29 pm
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Don't power companies use wattmeters, which compensate for PF?


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