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What does PFC do for you?

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Nov 11, 2003
Long Island, NY
I've always been wondering this one. I read up on it on some sites, but the explanations make no sense, or don't explain anything to me at all. Maybe im looking at the wrong sites, but in any case im not getting it. Can anyone explain the advantages of why we should use it or if it really is worth the extra money to buy? I spent extra to buy this TT-W0008 when it came out because it had Active PFC, and I think that this PSU is nothing special at all.

Also whats the difference between Active and Passive PFC


Jun 13, 2004
Grand Rapids, MI
Power Factor Correction (PFC)
Power Factor Correction (PFC) allows power distribution to operate at its maximum efficiency. There are two types of PFC, Active PFC and Passive PFC.

Active PFC
The preferable type of PFC is Active Power Factor Correction (Active PFC) since it provides more efficient power frequency. Because Active PFC uses a circuit to correct power factor, Active PFC is able to generate a theoretical power factor of over 95%. Active Power Factor Correction also markedly diminishes total harmonics, automatically corrects for AC input voltage, and is capable of a full range of input voltage. Since Active PFC is the more complex method of Power Factor Correction, it is more expensive to produce an Active PFC power supply.

Passive PFC
The most common type of PFC is Passive Power Factor Correction (Passive PFC). Passive PFC uses a capacitive filter at the AC input to correct poor power factor. Passive PFC may be affected when environmental vibration occurs. Passive PFC requires that the AC input voltage be set manually. Passive PFC also does not use the full energy potential of the AC line.

Oklahoma Wolf

Senior Warranty Validity Sealed Stick Remover
Mar 18, 2003
Here is a somewhat more accurate description of PFC (if a little wordy): http://www.dansdata.com/gz028.htm

PFC has more impact on the local power grid than anything in the computer. It's not at all necessary in North America where only industrial customers are billed for power factor, but nice to have anyway.