Active PFC

[xortam]

Is the PFC (Power Factor Correction) feature on the newer power supplies a worthwhile feature? I ordered a 400w SilverStone Super Silent Power Supply but I'm wondering if I should cancel and order the Active PFC version elsewhere. I just ordered the DC special edition SilverStone LaScala SST-DC03 w/ VFD so the HTPC can start to come together. They also recommended a 420w Enermax EG425P-VE which sports separate 12v rails and copper shielding. I wonder if the Enermax might be better for driving an HTPC. I want both dead quiet operation and stability for a 3.2GHz Intel CPU with DVD burner, HDDs, ATSC tuner, graphics card, etc.

[Chrono_Wanderer]

I think the power line is cleaner, that's all...

I personally look for Active PFC when i grab a PSU, price difference isn't that big

But its not like there's a big difference also

[xortam]

The price difference is normally about $10 but I already ordered so I'd have to get hold of them in the morning to cancel and hopefully not slow down my case shipment. I can actually get the PFC version for only a few dollars more elsewhere. What about the Enermax approach?

[Jon P. Inghram]

http://www.dansdata.com/gz028.htm

[Greebe]

How Dan goes onto say that with PFC correction will save you money and then turns around and states it will cost you more is just too funny.

PFC will reduce the current phase lag your home power meter does sense. But how much saving will you see when we're talking (lets say) 400w/h, not much compared to the total power load (as mentioned couch change annually).

Conversly PFC really does add up to a real world factor when you are a business/commercial entity. Typically welding shops pay the most for their power because of the horrific current distortion they induce into the power line and the peak demand they require.

When a manufacturing plant/mall/school.office building etc are considered the real world savings can be enormous. Typically saving the cost of the energy management system in the first year after peak demands have been reduced. A typical Mall for instance can save on the order of >$80k annually... hey that's my bonus!

[az]

Read closely, Greebe: He doesn't say active PFC will be cheaper. He says a salesperson might say that it'll save money, and goes on to say that said salesperson would be full of crap for uttering such a statement.

Xortam, for homes, active or passive PFC (or no PFC at all) makes no difference.

AZ

[xortam]

My concern wasn't cost of operation (never saw that mentioned as a feature) but rather clean power for an HTPC. The reviews on the SilverStone Striders seem to be quite good, both PFC and non-PFC.

[az]

PFC only affects the outside of the PC, not the inside. Mains current is "polluted" (not strictly sine, distortions, etc.) anyway, so your PCs PSU won't degrade sound quality by polluting your mains. If your Amp sounds bad when not fed with 100% perfect, clean sine current, it's poorly designed (which is often called "high end" and sold for outrageous amounts of money).

AZ

[rylan]

PFC generally gets higher efficiencies and reduces component stress in the power supply from abrupt load changes.

[UtwigMU]

AFAIK Active PFC is mandatory in EU and most PSUs sold here have it.

For instance, Antec has different models for EU, UK and US, of which former two have active PFC and the latter doesn't.

[Greebe]

Originally posted by az
Read closely, Greebe: He doesn't say active PFC will be cheaper. He says a salesperson might say that it'll save money, and goes on to say that said salesperson would be full of crap for uttering such a statement.

Xortam, for homes, active or passive PFC (or no PFC at all) makes no difference.

AZ

And just how did I know you were going to be the one to point that out AZ?

Yes I did read and he's full of shit for assuming that active would waste 10% power.

[Chrono_Wanderer]

:eeK:

relax guys.

[xortam]

Apparently PFC is a debatable feature for improving PC performance. I'd have to spend a little time digesting the Dan's Data article but I was hoping Greebe would have the skinny on how this affected PC operation. Sounds like he also thinks that PFC won't improve the fidelity. I thought I was picking up last night that low inductance components (light loaded motors, lighting, etc.) would negatively impact the clean power signals to the PC internals. Most of you say it only affects the "mains".

I cancelled my PS order last night (no confirmation of that yet) so I hopefully I can get the right part ordered today. Do you see any other advantage of the operation between the two Strider PS'es I linked?

[Greebe]

The net effect on the PS secondary is negligable, it's there to clean up the primary. One small but nice benifit is that if there are minor brownouts it should correct. End result is a cleaner running ship, for both the utilities and go juice your PC sees.

[xortam]

Thanks ... I'll probably be on an UPS and I may get a line conditioner but perhaps just for the TV.

I ran across this interesting comment:

Active PFC
Some newer power supplies have added active power factor correction (Active PFC) circuits that smooth and tone the power conversion process, making it much more efficient. Active PFC power supplies have a PF upwards of 0.95, meaning only a 5% or less power loss in the conversion process. As an important added benefit, the Active PFC process reduces harmonics in the power supply—vibration that creates both physical noise (like a high-pitched whine) and electrical noise. To deal with harmonics, electrical components have to work harder and thus burn out more quickly. Using Active PFC puts a lot less strain on the internal components of the power supply.

Bottom line? An Active PFC power supply converts energy efficiently. As an added bonus, it’s quieter and will last longer than a power supply without it.

I've also seen some comments that a PFC PS is actually noisier. I saw one "authoritative" comment that it will cut your electrical use down in half (I don't buy it). I understand that PFC PSes have actually become required in Europe (really?). It seems many HTPC folks are going for the PFC feature but I haven't collected that much data.

Overall I get the impression that it couldn't hurt and it probably will help. I cancelled my non-PFC PS order and got verbal and E-Mail confirmation to that affect but the shipping order summary included the PS. I guess I'll find out soon when the package arrives. I'll just scramble and pick up a PS at that time if they indeed did delete the order. I've been checking out some silent PC sites and HTPC sites and they seem to like Silenx, Fortron (and its many incarnations), Antec TruePower, and Enermax Noisetaker. Not too many people know about SilverStone but those who tested their PSes like them very much though the 12v rail isn't as steady as I'd like. None of the reviewers had any problem with their PS under various loads despite the 12v rail variance. It was noted that the SilverStone did an excellent job of moving the air and low fan speeds which is a big advantage over the favorite, the more expensive Silenx PSes.