11.98V on 12V Rail for Brand New PSU?

rewted

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Been a long time since I read up on power supplies in depth, but LTT and others have recommended the Seasonic Focus SGX-650 for my ITX build, so I got it and finished the build this weekend.

I'm looking at the various meters and from what I remember you should generally have 12V or (slightly) above available on the system. I've never not had a power supply read 12V on the 12V rail except this one.. the 5V and 3V's are fine.

Am I in for trouble here / should I replace it? My readings were at idle. It doesn't seem to budge much under load up or down. Wall power is all good, other systems are not having issues.

Thoughts?
 

rewted

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I've also never used Seasonic directly branded (I'm sure they OEM'd for someone) so a little out of my depth.
 

NattyKathy

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20mV is an absolutely tiny deviation from 12V, it'll be fine. Now if it were 200mV low that could be an issue but 11.98V is within spec.
 

rewted

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Figured, just thinking something brand new shouldn't be out of spec at all IMHO and if anyone else that has this PSU could chime in with their experience.
 

NattyKathy

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The ATX standard allows for a +/-5% tolerance range on the 12V rail, 11.98V is not outside of spec. That's only -0.16% difference from 12V; unless it drops enormously under load, it's fine. Personally I've never had a PSU that is exactly 12.00V, always a few tens of mV high or low. Not saying it doesn't happen but expecting exact voltage down to two decimal places from a consumer electronic box is unrealistic IMO
 

kirbyrj

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Figured, just thinking something brand new shouldn't be out of spec at all IMHO and if anyone else that has this PSU could chime in with their experience.

You're overthinking this one...especially if it works fine when using it.
 

hititnquitit

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What are you using to check the voltages with?
Use your multi meter to check your rails (both at idle and load) to verify what your seeing is accurate.
 

GiGaBiTe

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The ATX spec specifies that all positive rails should be within +/-5% of their rated voltage, and all negative rails should be +/-10%.

Unless the 12v rail is lower than 11.4v or higher than 12.6v, you're fine. Though you'd need something to be seriously wrong with the PSU to get anywhere near those numbers, or it'd have to be a shitty PSU with terrible regulation.

I've seen many shitty PSUs that went under 11.4v, but few that overshoot. I did have one garbage Coolmax "400W" unit that had the 12v rail at 13v though.
 
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The ATX spec specifies that all positive rails should be within +/-5% of their rated voltage, and all negative rails should be +/-10%.

Unless the 12v rail is lower than 11.4v or higher than 12.6v, you're fine. Though you'd need something to be seriously wrong with the PSU to get anywhere near those numbers, or it'd have to be a shitty PSU with terrible regulation.

I've seen many shitty PSUs that went under 11.4v, but few that overshoot. I did have one garbage Coolmax "400W" unit that had the 12v rail at 13v though.
Wow, did that 13V cause any issues?
 

cpufrost

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I would be more concerned with ripple and poor regulation than a rail voltage that is ever so slightly below what it should be. Load up your GPU with Furmark and see what it is. If it drops to 11.6 then I'd be concerned.
 

GiGaBiTe

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Wow, did that 13V cause any issues?
Surprisingly not. The only reason I noticed it is because I was in the BIOS changing some options and happened to open the hardware monitoring page. I glanced at the +12v rail and it said 13v and I was like WTF that can't be right. Pulled out my multimeter and it was indeed 13v. It promptly went in the trash after I stole the fan out of it.

I forgot where the system it came in came from, I just remember it being some Athlon XP with an ASUS motherboard.
 

cpufrost

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Remember to ocz psus with the adjustable pots? Lol
Yes I do remember those. Often, when regulation isn't the best the 12V rails are quite high in unloaded states and sag down considerably under heavy load up to OCP kicking in (if it's present) and oftentimes with those big single rail designs it becomes dangerous as a small gauge wire will glow red hot (big fire hazard!) without tripping anything!
 

GiGaBiTe

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Remember to ocz psus with the adjustable pots? Lol

Never owned an OCZ power supply, but tweak pots inside power supplies isn't uncommon. I've had to adjust many computer power supplies after repairing them to get the voltage rails back in spec.
 

cpufrost

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Never owned an OCZ power supply, but tweak pots inside power supplies isn't uncommon. I've had to adjust many computer power supplies after repairing them to get the voltage rails back in spec.
The OCZ units had user adjustable potentiometers right next to the modular connectors!
 

RazorWind

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Been a long time since I read up on power supplies in depth, but LTT and others have recommended the Seasonic Focus SGX-650 for my ITX build, so I got it and finished the build this weekend.

I'm looking at the various meters and from what I remember you should generally have 12V or (slightly) above available on the system. I've never not had a power supply read 12V on the 12V rail except this one.. the 5V and 3V's are fine.

Am I in for trouble here / should I replace it? My readings were at idle. It doesn't seem to budge much under load up or down. Wall power is all good, other systems are not having issues.

Thoughts?
How are you measuring this? With an actual meter, or with some sort of software thing on the system?

Is this with the system actually doing something, or just idling?

Edit: What happens if you look at the readings with the system actually doing something?
 

GiGaBiTe

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The OCZ units had user adjustable potentiometers right next to the modular connectors!

How did that not go badly. I hope the adjustment range was like less than half a volt.

Or did they have language in their user manual "tired of normal scrub power supplies with crappy 12 volts? with ours, you can send your system to 18 volts for maximum overclockability!"
 

cpufrost

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How did that not go badly. I hope the adjustment range was like less than half a volt.

Or did they have language in their user manual "tired of normal scrub power supplies with crappy 12 volts? with ours, you can send your system to 18 volts for maximum overclockability!"
It's a fad kind of like the car audio stuff. 13 is bigger than 12 therefore it's gotta be better! ;-)
Too much voltage is just as bad as too little. The regulators downstream just have to work harder keeping their outputs on target. Eventually something has to give. In the case with components carrying 100s of amps it often results in fireworks.
 

noko

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Been a long time since I read up on power supplies in depth, but LTT and others have recommended the Seasonic Focus SGX-650 for my ITX build, so I got it and finished the build this weekend.

I'm looking at the various meters and from what I remember you should generally have 12V or (slightly) above available on the system. I've never not had a power supply read 12V on the 12V rail except this one.. the 5V and 3V's are fine.

Am I in for trouble here / should I replace it? My readings were at idle. It doesn't seem to budge much under load up or down. Wall power is all good, other systems are not having issues.

Thoughts?
Wow, I never had a power supply that close to 12v, congrats. Your fine.
 

WilyKit

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If you’re using software monitoring then this thread is a big waste of everyone’s time
 
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