All fans run when system shut down

hi, i have a win 7 build with some strange fan behavior. the system runs great when booted up, however after shut down every fan in the box (cpu, gpu, psu, all case fans) begin to run at full speed indefinitely. this seems unrelated to the operating system, because if i disconnect power to the machine, hold the power button for 30 seconds to make sure all power is drained, then just plug it back in, all fans resume at full speed right away. when i start up the machine all the fans drop down to normal speeds. i'm also fairly confident it's not a hot cpu, when the machine is booted up/running, the cpu averages only 33 C, i doubt the cpu is magically heating up to dangerous temperatures when the machine is powered off :p

kind of stumped on this one, any thoughts?, thanks :)

i2600k currently at stock speeds
msi z77a-gd65
11 answers Last reply Best Answer
More about fans system shut down
  1. I have an msi motherboard and know that there are various fan settings in the bios.

    Have you checked the smart fan settings or tried resetting the bios??
  2. hey guys, thanks for the feedback. i should have mentioned, i've tried 2 different motherboards in this machine. i had an intel z68 board in there originally, it did the same thing for a while (fans full when off, worked fine / good temps when on), eventually it refused to post anymore with the "hot cpu" led lit up. this light would come on instantly as soon as power was supplied to the board even though the cpu has sat cold with no power for days. i figured the board was defective (bad heat sensor or something, and the bios code display had never worked) so i replaced it. the new board boots fine, everything works perfectly with the exception of the fan behavior, and post bios code "A0", which the manual is very vague about ("Onboard devices Initialize and Detect")

    i've tried resetting cmos on both boards, latest bios, tested psu with paperclip test (and computer boots up and has power fine), mobo and cpu power are all plugged in securely.

    please let me know if you have any thoughts,
    thanks for your time
  3. Best answer
    i can honestly say i think it is the psu... just try another one if you ahve it

    also another thing that it could be is the gpu do you have any others?
  4. well with 2 different motherboards we have ruled out bios

    Take panic's advice try a new PSU

    one other thought, this is a stupid question, but want to make sure I am covering all the bases, there is no extra or 3rd party fan control is there? no 5.25 bays with switches or rpm displays?? or anything like that??
  5. Which fans (CPU, chassis, PSU) fans are running and what are they plugged into?
  6. wow, thanks for getting me to try swapping the psu, i had to pull it out of another active machine so i never would have tried unless i had more reason to believe it was the psu...
    ocz pro 700w modular psu = fan problems
    $20 400w thermaltake = works great :P

    now i just need to decide if it's worth keeping the msi z77a-gd65, or get my money back and give the intel DZ68BC another try.
  7. hmm well i dont know i mean you already have it right... But glad it works and glad we figured out the problem! [:panicmaster85:3]
  8. Best answer selected by station.
  9. thanks again panic, went back to the old board and working perfectly with the alternate power supply, saved me time and money, should have asked here earlier :)
    anybody want an ocz 700 watt paperweight?
  10. [:panicmaster85:9] XD yes!
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