I want to transfer some internal peripherals (Wifi card, RF receiver) from my current mo-bo to a new one. Upon inspection it turned out they all have 4-pin internal USB connectors, connected to the board of the card-reader. So the card-reader acts like an USB hub for these devices.

My new mo-bo has no 4-pin internal USB connections, so I tried plugging in the connector onto the right-most part of a normal (9 pin) USB header. This should work in theory, and I made sure the wire colors (red/green/white/black) match the pins, but none of the peripherals work. Some result in 'Unknown device' in Device Manager, and others are not even detected.

Is there a logical reason why the above doesnt work?

EDIT: I just hooked them up on my old mo-bo again, and now they don't function there anymore. So I must have damaged the devices by connecting them in reversed pin order on the new mo-bo. When the connector is upside down, ground and power pins are swapped which must have damaged them.

So this explains why Windows doesnt detect them, and everyone trying the same: be very carefull with connecting internal USB cables!

  • Sounds like a good way to break something.
    – cutrightjm
    Jun 16, 2012 at 17:36
  • If I understand you, then it sounds like what you are doing should work as you expect. But colors aside, are you sure you got the USB cable on the right set of pins, based on what they do (+5V, D+, D- and ground) and what the motherbaord manual says the pinouts actually are? Are they the right way around (on both the montherboard and the card reader) ie: D+ and D- aren't swapped? Have you confirmed the card reader is compatible with the OS on the new machine? Does it still work as expected when you reattach it to the old system? Jun 16, 2012 at 17:40
  • 1
    You mileage here may improve if you describe details of the two motherboards in your hands (like brand and model for starters).
    – nik
    Jun 16, 2012 at 17:43
  • 1
    -1 It’s a warning, not a question.
    – kinokijuf
    Jun 17, 2012 at 17:06
  • 2
    @kinokijuf The answer is a good lesson for everyone, and I see nothing wrong with the question?
    – Maestro
    Jun 17, 2012 at 17:17

1 Answer 1


Those 9-pin headers are actually 10-pins. The 10th pin is usually missing or cut so that it is "keyed" properly and a typical USB connection isn't plugged in backwards or something.

The other thing to understand (and this may be critical) is that you're actually connecting 2 USB ports on that 9-pin header. Therefore, you need to be sure you're not mixing and matching the data signals between the two different USB ports. No real damage will occur but nothing will really work properly either. The other parts of the USB connection are very critical too and will supply the +5VDC and ground connection - be sure to get those right or you will almost certainly have problems.

On most mobo's where this 9-pin header is used (like all of them), one USB port will use the odd numbered pins while the other uses the even numbered pins. Not always, but usually. Be careful! Sometimes this header isn't even used for USB. Sometimes it's a RS-232 serial port header or it could even be a firewire 1394 port.

So assuming you have all the connections right, I would assume you maybe need USB drivers. Windows will usually detect USB but almost always get it wrong if you don't update the drivers from your mobo's manufacturer (at least, that's what I seem to always have t go through). Get the right drivers installed and you should be good to go. However, you may first have to apply correct chipset support by installing drivers or a patch for that before you can even think about installing USB support. (I can't say since I don't know what you have). However, once proper chipset support is working Windows just might detect the right USB stuff and you may not have anything more to do.

Hope it helps...

  • 1
    I guess I put the connector upside down, causing all pins to be reversed, frying the devices. I wasnt so carefull because I knew the wrong order wouldnt damage my mo-bo, but I forgot about the device itself :)
    – Maestro
    Jun 17, 2012 at 17:04

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