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# Power Supply / Fan Speed Concern

### #16 happyrock Posted 16 June 2009 - 09:42 AM

happyrock

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sorry I'm late but for the future and for anyone else that reads this topic...

the PSU you bought does not have PFC...

Non-PFC power supplies are no longer recommended. In Europe, power supplies are now required to have either active PFC or passive PFC.

What is PFC and why do I need it?
Switchmode power supplies without Power Factor Correction (PFC) tend to draw the AC input current in short bursts or spikes relative to the line voltage, The Power Factor of a power supply is technically the ratio of the real power consumed to the apparent power (Voltsrms x Ampsrms) and is a decimal between 0 and 1.0. If left uncorrected the Power Factor (PF) of switchmode supplies will generally be around 0.65 or less...
The Power Factor can be improved by using PFC circuits. These circuits “smooth out” the pulsating AC current, improving the PF, and reducing the chances of a circuit breaker tripping prematurely. There are two basic types of PFC, passive and active. Passive PFC circuits are less expensive and typically can correct the PF to about 0.85. Active PFC circuits are the most popular, are built into the switchmode power supply and can increase the PF to 0.98 or higher. The closer the PF comes to being 1.0, the better the performance of the power supply. Ideally, we want to end up with the input voltage and current waveforms being sinusoidal and in phase with each other...

A particularly important class of non-linear loads is the millions of personal computers that typically incorporate switched-mode power supplies (SMPS) with rated output power ranging from a few watte to more than 1 kW. Historically, these very-low-cost power supplies incorporated a simple full-wave rectifier that conducted only when the mains instantaneous voltage exceeded the voltage on the input capacitors. This leads to very high ratios of peak-to-average input current, which also lead to a low distortion power factor and potentially serious phase and neutral loading concerns...
Active PFC

The preferable type of PFC is Active Power Factor Correction (Active PFC) since it provides more efficient power frequency. Because Active PFC uses a circuit to correct power factor, Active PFC is able to generate a theoretical power factor of over 95%. Active Power Factor Correction also markedly diminishes total harmonics, automatically corrects for AC input voltage, and is capable of a full range of input voltage. Since Active PFC is the more complex method of Power Factor Correction, it is more expensive to produce an Active PFC power supply. ...
Passive PFC

The most common type of PFC is Passive Power Factor Correction (Passive PFC). Passive PFC uses a capacitive filter at the AC input to correct poor power factor. Passive PFC may be affected when environmental vibration occurs. Passive PFC requires that the AC input voltage be set manually. Passive PFC also does not use the full energy potential of the AC line.
Non-PFC

Non-PFC power supplies are no longer recommended.
if you want to give yourself a headache go here...and read about the Passive PFC and Active PFC..

Edited by happyrock, 16 June 2009 - 09:47 AM.

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### #17 rshaffer61 Posted 16 June 2009 - 10:04 AM

rshaffer61

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Thank you Happyrock and as always you are full of information.
I appreciate the assistance and information. I'm sure the OP has purchased the correct PSU and hopefully will have no more issues.
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### #18 happyrock Posted 16 June 2009 - 10:22 AM

happyrock

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your welcome... but no ...he did not get a good PSU...
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### #19 lhcbc Posted 16 June 2009 - 10:29 AM

lhcbc

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Toolate Happyrock. Already got a headache just reading what you wrote. Won't even attempt to delve further in the theory. But, I do have my TV and computer going through an Ultra 1000 AP, http://static.tigerd...ULT31502_1.pdf; which does have over and under voltage protection and spike protection. Everything I do has to be on a budget. I just try to cover the most important bases. Thanks ~ Britt.
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