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Case fans no longer spinning. Help me figure out why.

AkimboEGAkimboEG Mr. FancypantsWears very fine pants indeedRegistered User regular
edited September 2014 in Help / Advice Forum
Hi all,

I've just switched the PSU on my six year-old computer. After hooking everything up, I noticed the two front fans aren't spinning.

Relevant hardware:
Old PSU: Hiper Type R Mk-II 680W
New PSU: Corsair CX750M
Motherboard: Gigabyte GA-EX58-UD5
Front Case Fans: 2 * Arctic Cooling AF 12025 PWM
Rear Fan: 120mm Antec 3 Speed (came with case)
Top Fan: 140mm Antec 3 Speed (came with case)
The rear and top fans are both working fine. They both have little plastic switches to manually determine speed (L/M/H) and are powered by a molex from the PSU.

The front fans are PWM fans and only have 4-pin and 3-pin connectors (no molex). They're both daisy-chained to a 4-pin connector on the motherboard that's called SYS_FAN2.

I've tried switching them to two different 3-pin connectors, but that didn't help - they still didn't spin. (Switched back to 4-pin afterwards.)
SpeedFan and Gigabyte's EasyTune6 both didn't help. They just show fan speeds at 0.
BIOS has smart fan control, but only for CPU fan. Nothing for system fans.
When powering up the PC, I can see both fans spinning up for half a second before stopping completely.
Putting the PC under heavy load doesn't change anything.

A note - The fans are impossible to notice unless you're specifically checking to see if they're working. So I don't know if this only started after switching PSUs. Could be that they stopped working before the switch, and I've only noticed after since I was running with the case open to see that everything is running properly.

I don't have any extra case fans lying around to troubleshoot with. Also, the fact that they both spin up for a bit on boot makes me think the fans are actually OK, and I'm likely to encounter the same problem with new fans.

I've attached pictures of the daisy-chained 4-pin connectors and the top front fan.
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So, what could be the problem? What else should I check/test/try?
I'd really appreciate any help on this one.

Give me a kiss to build a dream on; And my imagination will thrive upon that kiss; Sweetheart, I ask no more than this; A kiss to build a dream on
AkimboEG on

Posts

  • iRevertiRevert Tactical Martha Stewart Registered User regular
    edited September 2014
    So stupid question but have you checked to make sure that they are plugged in at both ends?

    I'd double check and chase cable to make sure its connected.

    iRevert on
  • AkimboEGAkimboEG Mr. Fancypants Wears very fine pants indeedRegistered User regular
    The cable is permanently attached to the fan part, so no problem there. As for the motherboard connection, I've replugged it twice now. Also, the fact that they spin up for a bit on boot means they're getting power.

    Give me a kiss to build a dream on; And my imagination will thrive upon that kiss; Sweetheart, I ask no more than this; A kiss to build a dream on
  • bowenbowen How you doin'? Registered User regular
    There may be a second option in bios for the non CPU fans somewhere.

    I guess honestly I'd just go out and buy new fans just in case.

    not a doctor, not a lawyer, examples I use may not be fully researched so don't take out of context plz, don't @ me
  • iRevertiRevert Tactical Martha Stewart Registered User regular
    AkimboEG wrote: »
    The cable is permanently attached to the fan part, so no problem there. As for the motherboard connection, I've replugged it twice now. Also, the fact that they spin up for a bit on boot means they're getting power.

    You have to start small, I've had cables come apart so it was only getting power incrementally and was beating my head against the desk trying to figure it out. As said check settings and more than likely pick up some new fans and replace them.

  • PedroAsaniPedroAsani Brotherhood of the Squirrel [Prime]Registered User regular
    AkimboEG wrote: »
    The cable is permanently attached to the fan part, so no problem there. As for the motherboard connection, I've replugged it twice now. Also, the fact that they spin up for a bit on boot means they're getting power.

    It could be that on boot they are getting full voltage, and as things come online that voltage is dropping.

    Test the connections with good, known working fans. If you get the same behaviour, it is going to be more likely an expensive replacement (motherboard) a warranty return (PSU) or if you are lucky, a cable replace.

  • DaenrisDaenris Registered User regular
    if they're the same type of connectors you could swap the front fans with the rear fan you say is working to test whether it's the fans that are bad or something upstream.

  • yurnamehereyurnamehere Registered User regular
    edited September 2014
    When they stop, do they stop dead or drop off rapidly, or slow down very gradually? If the former, then it's likely the fans themselves are dying of mechanical problems.

    yurnamehere on
  • AkimboEGAkimboEG Mr. Fancypants Wears very fine pants indeedRegistered User regular
    Tested the fans on another computer, using the 4-pin connectors. Worked flawlessly. That means the problem is either with the motherboard or the new PSU. I doubt it's the PSU, since everything else is working fine, even a new and power-hungry GPU.

    I think I'll save myself some headache and just buy some new fans with molex connectors.

    Give me a kiss to build a dream on; And my imagination will thrive upon that kiss; Sweetheart, I ask no more than this; A kiss to build a dream on
  • bowenbowen How you doin'? Registered User regular
    Yeah that's a possibility, like I said, there should be something in the BIOS that controls case fans separate from the CPU fan. Probably in an entirely different location than the CPU one too.

    not a doctor, not a lawyer, examples I use may not be fully researched so don't take out of context plz, don't @ me
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