The PSU fan on my computer is not spinning at all. I've now run a high def video for 20 mins and it's still not spinning at all. I read there's power saving features that will power down the fan, but I'm really suspicious. (Read details below.)


  1. Is this normal behavior?

  2. If the fan may be optimizing for power usage, how I can test the fan? Ideally, without pulling it out of the case.


  • PSU Model: LSP Ultra 550W ATX Power Supply
  • All temperatures are normal or low according to SpeedFan. (CPU, HD0, Core, and other temperature monitors.) But I wonder if this detects the heat of the PSU itself.
  • I'm having trouble with a video card. The card might be busted. When removed (and using built-in video) the computer works fine. But sometimes that's a sign of a power issue. When the card is in, it won't display video but Windows seems to load. Video card worked fine 1 week ago, but then I physically moved the system. Could have been damaged in transport.
  • 1
    If it the power supply has a fan then it requires active cooling. If the fan isn't turning on its likely because its broken. What is your question exactly? The temperatures you are watching do not measure the PSU's temperatures, which is a concern, since your power supply controls power to everything. So if it fails while its running because it overheats, everything that it is connected to, can be damaged. Your video card problem is seperate problem from your broken PSU. – Ramhound Jul 1 '15 at 15:30
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    A PSU may have its own thermal control for its own fan, that varies based on only the psus own needs, they usually are totally unaware of your system temps. There are like no PSU fans that are controlled for any by the motherboard and its needs, although I have (myself) run a PSU fan off the motherboard for control before, they are not designed that way, and do not work that way normally. If the PSU fan does not address the PSUs own heat it is the PSU fan and its own controls. – Psycogeek Jul 1 '15 at 15:59
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    Some power supplies do not use the fan if internal psu temperature is low enough (seen one or two, some pricey corsair). But it should be on after a few minutes of cpu or gpu usage. – Dan Jul 1 '15 at 16:00
  • @Dan and others above: Thank you, all together, you've given me the answer: That this isn't normal and the fan is broken. – SilentSteel Jul 3 '15 at 17:05
  • @SilentSteel possibly but don't be too presumptuous. See the answer somebody posted asking you if the fan turns on momentarily when the computer is turned on. – barlop Apr 12 '17 at 4:08

If your temps are fine, then you're fine. If the fan turns on for second or two on boot and/or shutdown, then it's fine and it will only need to turn on when enough power is being used for it to need some cooling. Mines never turns on other than when it boots/shuts down which is just a way of checking that it works because it doesn't ever reach past 20% of its need total power capacity (which it only turns on when it's around 40% and up)

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