POLL about PSU: power quality conscience

Jerboy

Banned
Oct 27, 2001
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This will most likely something you never heard of. You're free to skip reading here if you never thought about buying a PSU separately.

The type of power supply in computer is called switch mode. The incoming AC current is converted to DC, and high frequency circuit converts DC into 5V, 3.3V and 12V needed by computers.

AC voltage is converted into smooth DC through a rectifier and a capacitor. This is a very simple circuit. This simple circuit has a habit of drawing very distorted current from the outlet contributing to "power pollution". By adding a circuitry called PFC(Power factor corrector), the distortion can almost be eliminated and helps reduce power quality problem throughout the power distribution network by reducing the amount of harmonic/distortion injected into power line. As with all improvements, this improvement costs money. Based on current power supply price, the price difference will be considerable.


European legislation requires all new computer PSU's to be fitted with a PFC to curb power quality issues. They're talking about adopting same policy on American market
power supplies. A 300W ATX power supply can be had for $20-30. Same power supply will cost $50-60 if it has PFC.

Without PFC, the power factor is ~0.6 and THD is about 120%. Ideally, PFC should be 1.0 and THD 0%. A PFC equipped PSU can achieve PFC~0.95, THD~20%.

Anways.. into the fun stuff..

Here's the scenario. You were buying a $35 300W generic PSU. The dealer offers free upgrade to either power factor corrected 350W Sparkle or 431 Enermax without power factor correction. Their normal price is same on both items.

Which option would you take?
1. Sparkle 350W PSU with power factor correction. I have a conscience to help improve power quality.
2. Enermax 431W, non-PFC. I want the extra 131W for margin and future over clockability, screw the power quality!

* for this question's sake, assume both of these power supplies puts out equal quality power at output and both equally sturdy and reliable. The only difference is available output power and presence of power factor correction circuit.
 

Czar

Lifer
Oct 9, 1999
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I would go with the 350w one, it has more than enough power and it has more steady power current so it wont damage your components.
 

kreno

Senior member
Feb 6, 2001
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Get the Sparkle, 350W is enough for just about anything really... Plus like you said, it helps with the "Power quality" thing. Go for that.... Sparkles are great quality and don't suffer from some of the probs that some of the enermax PSU's have experienced...
 

Jerboy

Banned
Oct 27, 2001
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Originally posted by: kreno
Get the Sparkle, 350W is enough for just about anything really... Plus like you said, it helps with the "Power quality" thing. Go for that.... Sparkles are great quality and don't suffer from some of the probs that some of the enermax PSU's have experienced...

Ok thanks for your opinion, but I think you missed my point somewhat. I picked the names Sparkle and Enermax for the heck of it. The question wasn't which one you'll pick based on each brand's reputation. It was about whether you'll take extra power for your own benefit or you'd settle with something less for everyone's benefit and conservation of energy. High power factor means effectively use of transmission lines and low distortion means less headache for the utility company. Reduced harmonic content in power line helps electric motors operate at it's peak efficiency, so you won't save any money on your utility bill, but you'll help save energy.
 

bozo1

Diamond Member
May 21, 2001
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Sounds like a bunch of horseplop to me. Any noise that could possibly be sent back outside of your house on a powerline would easily be filtered out by the isolation transformers that the power companies have all over the place.
 

kreno

Senior member
Feb 6, 2001
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He's european though, maybe they don't have nifty power line stuff like us... And I did read through your post, maybe I misread, terribly sorry dude.
 

Jerboy

Banned
Oct 27, 2001
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Originally posted by: bozo1
Sounds like a bunch of horseplop to me. Any noise that could possibly be sent back outside of your house on a powerline would easily be filtered out by the isolation transformers that the power companies have all over the place.

Not true. Harmonic distortion isn't "injected" into the line per se, but it is indeed caused by the load. Let's pretend you're pedaling your bike. Rather than evenly loading the wheels, what's it feel if you load it in pulsating patterns using the brake? Quite uncomfortable I'd imagine.

Power supplies without power factor correction does just that to our power line and causes voltage drop only on part of sine wave. When you load it with resistive load, voltage sag occurs evenly and can be compensated by automatic tapping transformers. Uneven voltage sang resulting in waveform distortion is very difficult to clean.