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PC inrush current reduction

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djsb:
I have had to replace 2 of my PC's power supplies under guarantee because of inrush current problems. I have looked at plugging the PC into a SurgeX AC power conditioner but they are mainly for using with power amplifiers.
As a PC is a more complex load does anyone have any suggestions on what I can use to soften/damp the inrush current? Would the delayed switching of damping resistors in series with the supply work or is it more complex than that?
Thanks for any assistance.

David.

Lightages:
It is not clear what your problem is. Are you saying that the power supplies are self destructing because of the sudden demand of your system when you start your computer? You have systems that draw that much power at startup? If this is what you are saying then there isn't a solution to limit the inrush current by limiting the current to the power supplies from the AC lines. If you try to limit this you can fry more things or the system will not start properly. What you need is bigger and better quality power supplies.

If you are saying the opposite, as in the inrush current that the power supplies are trying to grab from your AC lines and they are frying from not getting sufficient current during startup, then you need something more like a dedicated feed from the distribution box with larger wires, or a local full time high current UPS that can kick in when the current demand causes the voltage drop.

djsb:
To clarify this is one computer with a Corsair 650W power supply (HX650W). The power supply has a seven year guarantee so it is a good quality one. However they keep failing after around a year or so. This mainly seems to happen when I switch the PSU on with it's on/off switch at the back. The switch goes POP and then a little while afterwards the supply stops working. The supply is limited to 13 amps but for a very short time the inrush current exceeds this as is usual with switch mode supplies. Any ideas?

David.

ejeffrey:

--- Quote from: djsb on October 17, 2011, 09:08:46 pm ---To clarify this is one computer with a Corsair 650W power supply (HX650W). The power supply has a seven year guarantee so it is a good quality one.  However they keep failing after around a year or so.
--- End quote ---

The inrush current is a design parameter of the PSU.  It should be brief and of limited total energy.  If the supply does not limit the inrush to a level it can handle, the supply is not high quality regardless of the length of the guarantee.  The other possibility is something wrong with your mains supply: the voltage is too high or you have lots of surges.  If you have a poor line quality a filter might help, but it will do so not by limiting the inrush current, but by filtering out spikes and surges.

There is an outside possibility that the supply is just overloaded.  That could potentially lead to reduced lifetime although I find it highly suspect.  It is likely that the computer would become unstable and unusable due to brown-outs well before the power supply started failing from overload.  In any case, a higher capacity supply would solve that problem.

IanB:

--- Quote from: djsb on October 17, 2011, 09:08:46 pm ---To clarify this is one computer with a Corsair 650W power supply (HX650W). The power supply has a seven year guarantee so it is a good quality one. However they keep failing after around a year or so. This mainly seems to happen when I switch the PSU on with it's on/off switch at the back. The switch goes POP and then a little while afterwards the supply stops working. The supply is limited to 13 amps but for a very short time the inrush current exceeds this as is usual with switch mode supplies. Any ideas?
--- End quote ---
How often do you switch the computer on and off like that? It's a rare thing that I power cycle a computer at the mains switch, probably not more than once every few months. I always use the soft switch on the front of the computer and leave it in standby mode when not in use. It would not surprise me if that is the expected usage and is factored into the design of the power supply.

One other thing I have noticed is that if you switch off a power supply at the mains, you should let it sit for at least five minutes before powering it up again. If you switch it off and on within seconds you seem to get a much larger power surge than otherwise.

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