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Could unstable psu voltages cause problems?

Last response: in Components
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November 26, 2012 11:07:10 AM

Hello,
today i checked my psu voltages in bios ,
i saw that the +5v rail and +3v rail was fluctuating a little
the +5v is usally always at 5.080v but it sometimes goes to 5.120v for about 1 sec and comes back down to 5.080v in bios
is this a problem?
Anonymous
a b ) Power supply
November 26, 2012 11:13:49 AM

no
ATX specs let 12v, 5v, 5VSB, & 3.3v rails stay between +/-5% of their nominal value.
-12v rail is +/- 10%
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November 26, 2012 11:18:35 AM

but some people are saying that voltage on the rails must be "stable"
why are they using that word?
so does this mean that the voltages should not deviate from the 5.080v value that i get?
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Anonymous
a b ) Power supply
November 26, 2012 11:29:27 AM

any electrical source will never be perfectly the same constantly. stable is when it stays inside the the values.

seriously 0.04 is so tiny . . as long as you do not exceed more than .25 difference on the 5 volt rail it fine.
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November 26, 2012 12:06:05 PM

so is this because of the normal variations in load?(my psu is corsair cx 430 v2)
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Anonymous
November 26, 2012 12:13:32 PM

Check the Voltages when stress testing 100% CPU and GPU loads, if they drop below the specs (5%/10%) then yes you have a problem, minor fluctuations happen on every PSU, good or bad.
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November 26, 2012 12:19:13 PM

they never even drop or increase by 3% in any rail
3.3 v rail: 3.328 -3.310v
5v : 5.080 - 5.120v
12v : 12.000 - 11.988v
so these slight changes are due to the loads right?
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Best solution

Anonymous
a b ) Power supply
November 26, 2012 12:31:45 PM

no, they will fluctuate even when you idle.

you got a good PSU - the differences are fine.

stop worrying!
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November 26, 2012 12:38:49 PM

Best answer selected by assassin1234.
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a b ) Power supply
November 26, 2012 12:55:56 PM

Everything has a tolerance. When writers speak of "stable" voltages they mean "within tolerance". What kind of problems are you trying to attribute to voltage fluctuations?
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November 26, 2012 1:02:27 PM

ram1009 said:
Everything has a tolerance. When writers speak of "stable" voltages they mean "within tolerance". What kind of problems are you trying to attribute to voltage fluctuations?

i thoght this would cause crashes thats why i asked :) 
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Anonymous
a b ) Power supply
November 26, 2012 2:01:56 PM

assassin1234 said:
i thoght this would cause crashes thats why i asked :) 

i am glad to help.

your motherboard and graphics card have little power supplies on the called VRMs (voltage regulation modules) they are just like your power supply except they use DC/DC instead of AC/DC.

the motherboard has them for the cpu, memory and igpu if its on the cpu. the graphics card has them for the gpu and memory. they (the VRMs) fine tune the voltage even more. so as long as the PSU is within the specs, they VRMS are made to be able to handle it and provide "smoother" power to the components.

here is a review of a motherboard where the reviewer explained alot about digital VRMs
X58A-OC Review- MOST in depth!

here is a whole mess of stuff with links:
About VRMs & MOSFETs / Motherboard Safety with high-TDP processors

read that and you'll be an expert!
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