TechSpot

On-board USB q?

By h0ly_danc3r
Jan 4, 2006
Topic Status:
Not open for further replies.
  1. Is ti possible to use 5V power from molex to power up my on-board USB because i think there is something wrong with the power.I checked the cable connection couple of times and still the same message "Usb device has malfunction" when I connect device like my joystick to another USB it works fine.
  2. Nodsu

    Nodsu Newcomer, in training Posts: 9,431

    You can try.. There is a good chance of smoke emerging though :p

    You should start with making sure it's not a Windows/driver issue. Use a Linux CD and a USB mouse to test.

    Connecting a stub usb cable and measuring the voltages coming out of the port is another thing you should do before going and breaking anything.
  3. h0ly_danc3r

    h0ly_danc3r Newcomer, in training Topic Starter

    But the USB has 5v as the red wire from molex :confused: But tnx for advice I tried to connect mouse also same thing.
  4. Nodsu

    Nodsu Newcomer, in training Posts: 9,431

    You mean both the USB devices and the molex use 5V? Yes, that is true.

    But how do you know that the 5V from the PSU and from the mobo are exactly the same? If you connect the wires you may end up with your mobo trying to enforce 4.9V and your PSU insisting on 5.1V.. Not nice.
  5. h0ly_danc3r

    h0ly_danc3r Newcomer, in training Topic Starter

    Then I could try building a circuit that stabilize power from molex so it would be 5V always or something?
  6. Nodsu

    Nodsu Newcomer, in training Posts: 9,431

    It's not about stabilising. It's about shorting two wires with different potentials.

    What you can do is: cut the VCC line going from the USB controller to the USB port and connect the +5V from the molex to the port instead. Assuming the molex ground and the USB controller ground are not very different, things should work. That is if the USB controller doesn't expect the devices to draw current from VCC. Don't know that much about USB.
  7. h0ly_danc3r

    h0ly_danc3r Newcomer, in training Topic Starter

    Tnx alot man :angel: :angel: :angel:
  8. Nodsu

    Nodsu Newcomer, in training Posts: 9,431

    Jesus.. You are eager to break stuff. Just don't blame me when you end up with fireworks on your desk :p
  9. h0ly_danc3r

    h0ly_danc3r Newcomer, in training Topic Starter

    i won`t i will just use my trusty axe to finish him if something go wrong :D
  10. KingCody

    KingCody TechSpot Guru Posts: 1,568   +7

    ... or you could get a new mobo :giddy:
Topic Status:
Not open for further replies.


Add New Comment

TechSpot Members
Login or sign up for free,
it takes about 30 seconds.
You may also...


Get complete access to the TechSpot community. Join thousands of technology enthusiasts that contribute and share knowledge in our forum. Get a private inbox, upload your own photo gallery and more.