# Active PFC - What is it, & How Important is it ?



## Girderman (Oct 22, 2006)

I built my "dream system" about 6 months ago with some "windfall" income. Spent about 2 full months researching each individual component. For the Power Supply, I finally decided on the OCZ-520 12U because it had certain features I considered to be important, such as modular cabling.

OCZ ModStream OCZ-520 12U Power Supply | silentpcreview.com

Another "prime" feature I thought it had was Active PFC, which is the point of this question/post. During my research, I was under the impression that if a PSU had Active PFC, it's efficiency would be very high. Having read many posts regarding the difference between what a PSU claimed to be able to deliver and what was actually put out, I regarded this to be very important. For some reason (I think I read it somewhere) the efficiency of the PSU's with Active PFC was supposed to be a consistant 98% or so of rated output.

I've used the PSU for 6 months with no apparant problem, however while looking back at my purchase I've discovered that this Power Supply does NOT have Active PFC, and I am wondering how important of a feature that is to be missing.

HOW it happened is fairly interesting, and I'll post that here also, on the chance that I might save someone else from the consequences of my mistake.

I was shopping 4 internet computer hardware vendors: NewEgg, ZipZoomFly, Monarch and mWave. Since NewEgg has the best search engine, I would compare technical characteristics between particular pieces of gear and, once I was interested in a specific item, I would do a comparison of cost between the 4 vendors mentioned.

NewEgg listed the OCZ-520 12U as having "Active PFC", but I found a better deal at Monarch, so assuming both PSU's were identical I purchased from Monarch.

Then I found out 6 months later that OCZ sells two different "OCZ 520" power supplies. The suffix "12U" means it is intended for sale in the US, and the suffix "12*E*U" for sale in europe.

I've discovered that only the European model has Active PFC.

What I'd like to do now is assess whether or not to get rid of the PSU and purchase a better one. It seems adequate so far, but I am running an overclocked Opteron 165 with 3 hard drives, a DVD burner and 2 - 120mm fans, and cannot say for sure that some of my "odd" symptoms may not be caused by an inadequate PSU.


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## Tumbleweed36 (May 14, 2005)

Hi,

If you get time, take a few minutes to read the power supply information link under my signature, because this will answer your questions. What you need to know is that some European countries require Active PFC while the USA does not require it. Therefore, the companies do not bother (more expensive to produce) to put that feature in some supplies sold in the USA. Most high end suppies do have that feature.

While I prefer the Active PFC, I would not bother to change a power supply simply because it does not have this feature. Therefore, read about it, be informed before your next purchase, but use what you have until you decide to build a new unit.

Last, but certainly not least, the OCZ supplies are excellent quality regardless of whether they incorporate the Active PFC or not. I don't think that not having Active PFC in your OCZ supply would have any adverse performance factor on your rig.

Hope that helps and be sure and read the Power Supplly Information.

Post back with questions/concerns.


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## linderman (May 20, 2005)

Tumbleweeds advice to read the PSU selection thread is an awsome idea, given that most ALL computer builders & hobbiest are bound to learn soemthing in there.


As found during my experience, units wihout active PFC tend to be about 70% efficient at best. I would use the calculator in the PSU thread and check your load >>>> dont forget to add 30% to the end result for unit inefficiency.

And to answer another statement above, the BEST pus units I have seen so far top out at 85% efficient but there are far more 70's units sold for the budget minded then they are models availalble that are 80% and above

hope you enjoy your read, the fellas but lot of effort into that one!


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## TomBrooklyn (Nov 28, 2005)

Tumbleweed36 said:


> take a few minutes to read the power supply information link under my signature


 Hi. I don't see the link. Could you post it again?


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