I've got a ASUS ROG Maximus V Extreme and I'm trying to connect my fans to the chassis fan pins to get them running according to the motherboard. I know for sure that my fans work, as when I test them with my Molex connector, they all happily power on.

Here's two of my chassis fans connectors (there are 3-4):

enter image description here

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Here's the connector that came with either my motherboard or the PSU, can't remember :)

enter image description here

I've never seen one of these strange cables before. All I know is that if I plug in the 4-pin mobo connector to either of these fan plugs, fans don't come on and don't show up in the BIOS. (Motherboard has a crazy awesome UEFI BIOS and shows you if it sees the fans.) If I try plugging the 4-pin connection into the mobo and the other side into the PSU, I can't POST. If I plug the PSU connector in without the mobo connector, fans come on.

What could I be doing wrong here? Is it a problem with the cable I'm using? Is there something I may have missed in the build?

  • 1
    I have an older IDE system with a floppy drive (!). The power for the FDD uses that small connector/molex adapter on the right. – WindowsEscapist Nov 30 '12 at 16:58
  • 1
    Yeah, Don't plug the mini-Molex into the motherboard, the only power is the 4/8pin by the CPU and the 24pin on 99% of consumer Mobos... You are lucky the only thing was that it didn't post since you were back-feeding power in. My old Asus ROG rarely fired up the fans until they were required. In the BIOS there are chassis fan options such as "Cool & Quiet" and "Silent", etc. In short they do not always run, nor need to. Try the BIOS and then benchmarking with 3dmark and see if they kick on. Just keep an eye on temps, but my bet would be they aren't dubbed as needed by the bios yet. – nerdwaller Nov 30 '12 at 17:04
  • This isn't your average consumer motherboard... this is the Maximus V Extreme. So my Chassis Fan pins don't really do anything? – Naftuli Kay Nov 30 '12 at 17:45
  • @WindowsEscapist so do I need to buy another cable then? Is it simple cable incompatibility? – Naftuli Kay Nov 30 '12 at 18:44
  • I really don't know much more about it - quite possibly. – WindowsEscapist Nov 30 '12 at 18:56

You are referring to a floppy power connector. It does not connect to the motherboard. The connection on the motherboard is where you connect the cable from the fan.

If you don't have a floppy drive, leave this disconnected.

Floppy connector is the lower left connector in this image. enter image description here enter image description here

| improve this answer | |
  • Where can I get a cable that adapts from the 4-pin motherboard connector to molex as shown above? – Naftuli Kay Dec 2 '12 at 4:02
  • Most electronic stores, like Radio Shack, have them. – CharlieRB Dec 3 '12 at 13:23

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