power supply - Computer is OFF, and fans turn on and off twice a day

05
2014-04
  • Wouter

    We have an OptiPlex 755 desktop acting quite strangely here. It's powered off, not in standby or hibernate, and from time to time it will just start spinning its fans for a few seconds, and then turn off again. (The PSU doesn't have a power switch, so the main board is still getting power.)

    My guess is that this is a PSU-issue, since this is also the behavior these computers have when you disconnect/connect the power cable. Yet, when using the computer, there are no noticeable power-interruptions.

    Has anyone seen this kind of ghost-computer behavior? Might dust-cleaning the PSU solve it? Or is it more likely to be a component-malfunction?

    • Answers
  • janis.miska

    My experience tells me it`s PSU! 97,5% :)

    Had this problem several times! Easiest way to diagnose is to try working/trusted PSU.

    I have used non-Optiplex form PSU, but just any with enough power (Watts) and compatible mainboard connector 22/24 pins etc borrowed from my friends/neighbours.

    Remember to charge off motherboard with on/off button after removing old PSU to avoid short!

    Good luck!


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  • themacfreak

    My desktop computer (Zotac 8200 motherboard) has a problem when I put it into standby mode. I use Windows 7 to put it into standby. The cpu fan, system fan, and PSU fan don't turn off. Nor does the power light in the front of the computer. I can't find any settings in the BIOS that all me to control this strange behavior. The computer can resume successfully from standby so it isn't froozen. What can I do? Thanks


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  • MDMarra

    In your BIOS you should look for something like Standby/Sleep State or Power state, and make sure that it says S3 and not S1, which will leave the CPU on, which will require cooling.

  • blah

    lol thanks for the evolving errors Microsoft. I just installed windows 8.1 on a fresh unaltered out of the box ssd's in raid0 setup and it wont shutdown. Or power down.

    and by shutdown I mean QUIET. no fans or blinky lights... this new feature called hibernate ha doesn't sound like it. as for sleep if they meant shut off the monitor and keyboard / mouse lights. that works great. all these configurations can be implemented through our complicated options tabs via desktop gui or bios. but turn off the fans = hold down power button for 4+ seconds on all atx cases. DONE. magic... tools.

    ps my x58 motherboard could use a s4 or perhaps a s6 version if pos and (s3) don't work :P