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Thread: Low voltage on the 12V rail in a brand new Cx450

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    Default Low voltage on the 12V rail in a brand new Cx450

    Hello everyone,I have a system with the following configuration:

    I5 cpu,gigabyte b75 d3h mobo,4+4=8gb DDr3 ram,750ti gpu,3 hdds.

    For the last few months,i have been using a Corsair VS450 psu to power this build.However i have been growing increasingly concerned about the reliability of this psu as vs series psus are generally regarded as lower tier products.Also i used to observe that during load conditions the voltage on the 12v rail of this psu dropped to around 11.73 volts(as reported by HWinfo64-also please note that during idle it was around 12.1V).

    So i decided to change this psu recently and opted for a CX450 as its supposed to be a 80plus certified unit and therefore more reliable than a vs450(at least in theory).

    However much to my dismay,upon installing this psu i discovered that the voltage readouts on its 12v rail were even lower-during load it was dropping to around 11.66V and while idle it was at 11.95V!

    I am really shocked by this-i was under the impression that in corsair's newer CX series psus (that employed a Dc-DC type design),voltage regulation would be a lot better than other lower grade products that employ a group regulation mechanism(such as the vs series psus).

    Is there some kind of a problem with this psu or could the readings that are being provided by hwinfo possibly be erroneous?If its indeed providing 11.6 v under load,then would it be safe to continue using this psu for any length of time?

    Heres a screenshot of hwinfo that i took when i was using my vs 450:

    https://imgur.com/a/YSQkC

    heres another one that was taken today after installing the cx 450:

    https://imgur.com/a/FmFG5

    Does it indicate that i my newly bought CX 450 might be defective?Please check and advise,thanks.

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    a) That's still a safe voltage, but nope, not a good result.
    b) Try to measure that with a multimeter. Software readings are damn imprecise!

    The Cybenetics report on the CX450 shows an excellent voltage regulation for a decent unit https://www.cybenetics.com/code/pdf.php?id=VUm so no, 11.6V real reading doesn't seem good, but coming from HWinfo, I wouldn't trust it.

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    Quote Originally Posted by ssm002 View Post
    and opted for a CX450 as its supposed to be a 80plus certified unit and therefore more reliable than a vs450(at least in theory).
    VS450 is 80+ certified too, and efficiency isn't a measure of reliability at all.

    You didn't actually measure any voltage. HWinfo isn't a multimeter that plugs into the cables of your PSU, so whatever readings you got are inaccurate. You can't tell what is the voltage unless you measure it yourself.

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    Whats the proper procedure to test the voltage on the 12v rail using multimeter? Do i have to disconnect the psu's 24 pin connector from the motherboard to carry out this test or can it be done while the connector is still attached to the mobo?

    I am not very keen on removing the 24 pin connector from the motherboard as doing so is a very cumbersome process and requires a lot of effort.Therefore if there's any way to test the 12v rail without removing this connector,then i'd definitely like to know it.Can the readings be taken from a molex or a pcie connector somehow?If yes,please give me some pointers/suggestions on the right way to do it.

    Assuming that this psu is indeed putting out 11.6v under load,would it be safe to continue using it?Can it damage any of the components of my system in the long run?

    Would the system manifest any signs of instability if the voltages on the 12v rail dropped to unsafe levels?

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    Quote Originally Posted by ssm002 View Post
    I am not very keen on removing the 24 pin connector from the motherboard as doing so is a very cumbersome process and requires a lot of effort.Therefore if there's any way to test the 12v rail without removing this connector,then i'd definitely like to know it.
    Maybe that's the issue. Maybe the 24-pin isn't plugged in all of the way now and causing low voltage readings.

    But, as others have said, software like HWinfo is no way to check a PSU's voltages. It's getting it's readings further down the line at the motherboard.

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    I made some test for view the differences between the actual HWinfo (latest version) readings and a multimeter with 5 digits.
    In idle HWinfo readings measure 12.194 - 12.096 at 12 v rail, but the multimeter indicate 12.023. With aprox 40℅ of PSU capacity load, HWinfo readings is between 11.986 - 11.804 but the multimeter readings indicate 12.011v at PCI-e and CPU connectors, and 12.019v at molex and sata connectors. Thats a HUGE difference. We can't rely on HWinfo or any software of this kind readings, simply because they are not accurate. The same apply with the minor rails, in HWinfo it fluctuates but the multimeter show rock solid stability, frozen values.
    In the past i was made also this kind of tests (different versions of software, motherboard brands and configurations) and always was HUGE differences.

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    Yeah. And there is even difference between the measured connector
    Last edited by breixobaloca; 12-14-2017 at 11:03 AM. Reason: Confused

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    Quote Originally Posted by Al3xand3r View Post
    I made some test for view the differences between the actual HWinfo (latest version) readings and a multimeter with 5 digits.
    In idle HWinfo readings measure 12.194 - 12.096 at 12 v rail, but the multimeter indicate 12.023. With aprox 40℅ of PSU capacity load, HWinfo readings is between 11.986 - 11.804 but the multimeter readings indicate 12.011v at PCI-e and CPU connectors, and 12.019v at molex and sata connectors. Thats a HUGE difference. We can't rely on HWinfo or any software of this kind readings, simply because they are not accurate. The same apply with the minor rails, in HWinfo it fluctuates but the multimeter show rock solid stability, frozen values.
    In the past i was made also this kind of tests (different versions of software, motherboard brands and configurations) and always was HUGE differences.
    What i'm about to say is a very simple calculation, but it's indicative of what i'll try to say:
    From your very useful readings, certain data are produced that we can use as a given (*i have highlighted them with red colour).

    -So, by taking an average value from HWinfo measurements we have:
    11.986 + 11.804 /2 =11,895 (*HWinfo average value, -very simplistic calculation of course in order to make my point- ).
    So, when the actual readings from multimeter show: 12.011v, HWinfo shows : 11,895 average.
    -But, our friend the OP says that his HWinfo shows : 11,660.
    So, if we take @Al3xand3r's calculation as a given, this leads to the conclusion that IF the OP was able to use a multimeter, he would get as a result something that could be close to this:
    X=12,011 * (11,660/11,895) => X=11,773v (*IF he was able to use a multimeter).

    P.S. As i said at the beginning of my post, this is very simplistic calculation that might ignore lot of parameters, but nevertheless, in my opinion it can give us an indication that something isn't right
    (EDIT: hmm, from what i saw at CX600 review https://www.techpowerup.com/reviews/.../CX600M/5.html , this series voltage regulation is very mediocre, so there is probably nothing wrong with the PSU, probably these are its normal values!!) .
    P.S 2: Jonny's proposal sounds very logical. Take-out the cable from your mobo, connect it again and check what happens.
    Last edited by sith'ari; 12-14-2017 at 07:07 AM.
    CPU:Athlon 64 FX60 (2-cores) 2,6GHz
    Mobo:Asrock 939a785g
    cpu cooler:ArcticFreezer13 CO
    RAM:4 GB DDR 400MHz
    GPU:Asus 750 Ti 2GB
    PSU:Seasonic Platinum 660
    Monitor:Asus VE228HR
    Tower:Coolermaster Elite 430

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    Quote Originally Posted by jonnyGURU View Post
    Maybe that's the issue. Maybe the 24-pin isn't plugged in all of the way now and causing low voltage readings.

    But, as others have said, software like HWinfo is no way to check a PSU's voltages. It's getting it's readings further down the line at the motherboard.
    Can i test the voltage by taking the readings from a molex or pcie connector while the 24pin atx connector is still attached to the mainboard and the computer is operational?Could it possibly cause any issue with the mobo or the power supply if i attempt to do that?If there's no harm in doing so,please let me know the proper procedure to test the voltage from either a molex or pcie connector as i hardly possess any experience in this regard.

    And would it be ok if i disregard the software readings altogether and continue using this psu as long as i dont run into any serious problems?What symptoms am i likely to observe if the voltage on the 12v rail goes to unsafe levels?

    As far as i can remember,the 24 pin connector was plugged in securely-but i will still try to check it once just in case.

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    Quote Originally Posted by ssm002 View Post
    ....................

    As far as i can remember,the 24 pin connector was plugged in securely-but i will still try to check it once just in case.
    yes, before anything else do this 1st, and check again your HWinfo readings to see if something has changed at its values. (*and also, since you'll open your PC, i would propose you to make a thorough check at all the cables, not just the mobo's)
    CPU:Athlon 64 FX60 (2-cores) 2,6GHz
    Mobo:Asrock 939a785g
    cpu cooler:ArcticFreezer13 CO
    RAM:4 GB DDR 400MHz
    GPU:Asus 750 Ti 2GB
    PSU:Seasonic Platinum 660
    Monitor:Asus VE228HR
    Tower:Coolermaster Elite 430

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