What is PFC?

[Fryguy8]

See it listed on power supplies on newegg, was wondering what it meant, and if it's important or not.

 

[dream caster]

It is a measure of the percentage of input current (from mains) that is doing some work and being used by the PSU; if it is high it means also that PSU is sending less interference to other appliances in the same power circuit; but really it is not important for the computer being powered. The maximum posible is 1 (or 100%).

 

[64bit_is_here]

see the thread "which 500~W PSU". at the end of that thread it is explained very clearly what PFC is.

Hope this helps

 

[64bit_is_here]

EDIT

 

[Ice Czar]

PFC Decoded by that master of making the technical understandable and funny
dan, of dansdata

 

[Fryguy8]

so it has nothing to do with actual computer performance, only consumed electricity?

 

[Ice Czar]

well its not even the consumed electricity per se
and there is a possible performance metric, depending

Active PFC PSUs may also deal with lousy mains power better than passive PFC units, but PC PSUs generally handle spikes and surges and dropouts pretty well already, and a proper outboard power conditioner is a better solution to that problem, anyway.

offset against

Passive PFC is just compensatory capacitance or inductance across inductive or capacitive loads; it tries to iron out the oddities with passive components.

Active PFC is an actual second circuit. It sucks power from the mains in a resistive way, and feeds it to the low power factor circuit on the other side, isolating the mains from whatever that circuit is doing. Active PFC can iron out lousy power factor better, but it's less efficient, not more; an active PFC circuit will waste some power (at least 10%, in this case) as heat, just like every other circuit in the world.

additional heat that youd have to deal with

PFC however its not something you should go out of your way to aquire
getting a Power Supply with tighter Voltage Regulation, better Transient Response, lower Noise and Ripple and above all adequate amp distribution per rail are all far more important metrics, if it has PFC so much the better'

The small amount of extra heat would hardly impact a typical thermal solution, if it does, you have other issues to address, its just the efficiency loss of that circuit not the entire PSU.

A higher efficiency PSU is an added bonus, and many of those are PFC supplies, but its generally considered a minor metric,unless your into the silent PSU scene, the overall efficiency of a power supply largely denotes the heat it will put out

An 80% efficient PSU is converting 20% of the energy it draws directly as heat, the other 80% is eventually converted into heat by the computer as well after producing useful work less its own inefficiency, also the efficiency varies depending on the actual draw.

PFC is required in most countries overseas, but not in the USA, its certainly not going to hurt anything