Wire color codes

Hey!

just have a quick question.

is a black wire always ground and red always 12/5 volts?

and in the manual of my sabertooth z77 motherboard it lists the different "functions" of the 4 pin fan-connenctors. one is ground, cpu pwr, cpu in and pwm.
what is cpu in and what is the difference between cpu in and cpu pwr?

sorry if this is the wrong place..
18 answers Last reply
More about wire color codes
  1. Wire colors on ATX PSUs are standard. Some vendors like Dell have bastardized standards that may have slightly different connector pinouts and wiring color schemes.

    The pins on 4-pin dan header are ground, power, RPM-sense and PWM speed control.

    On PC PSUs, red wires are 5V but most fans use red for 12V. Black is almost universally DC ground inside DC systems.
  2. so if I have a pump with 2 pins and connect in to the motherboard, the black wire has to go to ground and the red to power (or CPU pwr, as my motherboard manual calls it)
    right ?
  3. Yes, thats correct
    Moto
  4. can I connect the 24 pin to the motherboard without powering the CPU ?
  5. You mean without plugging in the 4/8pin ATX plug for the Cpu? you can, but it won't boot, what are you trying to achieve by plugging the 20+4 pin in on its own?
    if you are trying to prime the pump then you bridge (short with paperclip) the green wire and one of the black ground wires next to it, that starts the Psu up and lets you fill a loop
    Moto
  6. I know, I have tried. But is it correct that some new PSUs have a failsafe to prevent jumping ?
  7. Not that I've heard of,
    I'm googling though to check :)
    Moto
  8. winther said:
    I know, I have tried. But is it correct that some new PSUs have a failsafe to prevent jumping ?

    They do not have "jumping protection" but some PSUs may fail to work properly if their minimum load requirement on one of the rails is not met.

    There are at least two ways for under-load to cause problems in bulk-regulated PSUs:
    - stray inductance increasing under-loaded secondary outputs to rise until over-voltage protections trip because the load drains less power than what is being provided by the HV transformer's stray inductance
    - insufficient load on the primary regulator output causing the PWM's duty cycle to be too low to provide sufficient power to secondary outputs, causing secondary output voltages to drop until under-voltage protection trips

    Most PSUs will work fine without external loads either because their design is (at least theoretically) immune to those problems such as DC-DC secondary outputs and others deal with the problem by adding circuitry or resistors to provide the minimum loading required for "no-load" operation.
  9. Usually (almost always) orange is 3.3, red is 5v and yellow is 12v.
    Black is ground.

    Dell power supplies use a different pinout but I believe the same colour codes.
  10. how do I know if my PSU isnt under enough load?

    I have the Corsair AX750 Gold..

    and how do I give it enough load without powering any major component ?
  11. winther said:
    how do I know if my PSU isnt under enough load?

    Most PSUs will work without external loads. PSUs that need external loading should shut down just like they should for an overload or other faults it has protections for.

    If a PSU needs "convincing" to stay on due to under-loading and you are wary of adding components to determine if under-loading might be the cause, you can use resistors to provide load. 1A per rail should be more than enough to make those PSUs happy.
  12. well the PSU doesnt just shot down.. its as if it just only supplies half or a quarter of the power its intended for, if you know what I mean?
    if I put a corsair fan on its starts, but at very low RPM, if I put a noctua fan on it needs a puch before starting, also spins very slow I think..
  13. winther said:
    if I put a corsair fan on its starts, but at very low RPM, if I put a noctua fan on it needs a puch before starting, also spins very slow I think..

    That does sound like the the PSU feedback loop is on an under-loaded rail and that the PSU might not have under-voltage protection.

    Use a multimeter to find which rail is closest to nominal value, put a 1A load on it (3.3ohms for 3.3V, 5.1 ohms for 5V) and see if that straightens things out. If you have no idea how to do that, ask someone you know who might have the parts and equipment to do it for you.
  14. btw I have just tried connecting the 24 pin to the motherboard and the pumps to the motherboard and then press the on button on the case but only a fan on the mobo startet spinning, not even the fans connected to the case's fan controller (the fancontroller is connected with a molex to the PSU)
  15. I just tried connecting the 24 pin to the motherboard and 2 x 200mm fans directly to the motherboard (plus the ones connected to the fan controller that I talked about in the last message) and the pumps to a molex..

    ONE of the 200mm fans started, then stopped after a few seconds and then started again, and started again and so on.. the other 200mm fan didnt start at all..
  16. Plug the Cpu line in as well, a la normal practice
    if things aren't playing well then, theres likely an issue with your Psu,
    Moto
  17. I'm not an advocate for Dell but, what did they have to do with this thread ?
    Their psu's use a mix of white and yellow wires for 12v
    They have used a standard ATX pinout since the introduction of the Pentium 4, when will people get over it ?
  18. winther said:
    ONE of the 200mm fans started, then stopped after a few seconds and then started again, and started again and so on.. the other 200mm fan didnt start at all..

    The POST "boot loop" is usually either a PSU problem or CPU/RAM/motherboard problem. Don't forget the ATX12V/EPS connector.
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