How does PFC work??

[alphakp295]

i was looking for a psu for the replacement of antec sp-500;
i found out few psus i like... but there was thing about PFC..
I was thinking of getting one of followings:
Kingwin Mach 1 600W
Xclio Greatpower 600W
Hiper Type R 580W

i noticed that Kingwin has +3.3@35A, +5V@48A, +12V1@20A, +12V2@20A, -12V@0.8A, -5@0.5A, +5VSB@2.5A;

Xclio has +3.3V@30A, +5V@28A, +12V1@18A, +12V2@18A, +12V3@18A, +12V4@18A, -12V@0.8A, +5VSB@3.0A;

Hiper has +3.3@30A, +5V@36A, +12V1@20A, +12V2@18A, -12V@0.8A, +5VSB@2.5A

Is 28amp on +5v little?
It seems like a big difference between 48amp and 28amp...

also, what's PFC?
My Seasonic S-12 had no PFC but I couldn't tell any difference...
only Xclio from above has PFC active.
What's the disadvantage of not having PFC in psu?

thanx for your prompt replies in advance.

 

[doolittle]

PFC attempts to reduce the phase angle difference between the voltage and the current on the AC input.

It doesn't make a whole lot of difference for the home user since most consumer home AC power meters measure real power only and not reactive / complex power (the difference in the AC voltage / current phase). For an office or datacenter FPC can make a difference since you have have hundreds or thousands of power supplies and without it your AC wave can get really distorted with harmonics.

efficiency is more important than PFC.

The +5v isn't as important as it used to be years ago (the XP socket a's liked high +5v) so for a modern system 28A on +5 is just fine.

 

[little_scrapper]

what's PFC?
My Seasonic S-12 had no PFC but I couldn't tell any difference...

From the seasonic S12 website:

Active Power Factor Correction [99% PF]
Reduces line loss & power distortion.


The S12 does in fact have PFC