Can I use a 4.5VDC power supply with 1A with a device that should have a power supply with 5VDC and 1A?

25
2014-04
  • user175061

    Can I use a 4.5VDC power supply with 1A with a device that should have a power supply with 5VDC and 1A?

    I have a hdmi splitter that needs 5VDC and 1A max but I can't find those ratings of voltage, only 4.5V, will it be enough? I measured the voltage and it's 4.57V. From what I know I don't think this will be a problem.

  • Answers
  • Hennes

    It may work, it may not work.

    Basically, for things to work you would need to:

    1. Have the same voltage.
    2. Be able to supply at least the same amperage.
    3. Have a correct connector (center pin negative vs center pin positive is not always obvious, but is a good way to release that magic smoke. So make sure polarity matches).
    4. Same kind of power (AC vs DC).

    Your voltage is close but 4½ volts is still a full fifth less then 5 volts. That may be to much of a difference. Noone is going to guarantee that that will work without knowing much more about whatever it is you are trying to power.

    Bottom line: Unless you do not care about replacing your HDMI splitter or the devices connected to it I would not try it.


  • Related Question

    PC power supply & normal range for voltages reported in BIOS hardware monitor?
  • Chris W. Rea

    I'm trying to diagnose whether my computer has an ample power supply. Sometimes when I play a video-intensive game, both monitors lose the video signal, even though the computer remains on and sound playing. A theory I have is: the video card isn't getting sufficient power. I can't imagine it's overheating because the machine is well-ventilated and the video card isn't hot to touch when this happens.

    Anyway, in my PC's BIOS there's a Hardware Monitor page, and among other voltages reported (such as CPU, DRAM, South Bridge, etc.) I can see the following values:

    3.3V    3.152V
    5V      4.944V
    12V     11.872V
    

    Are those the voltages used by peripherals? What voltage should I be referencing if I want to know what my video card (PCI Express) is consuming?

    What is the normal range of values reported for those? My values above appear to be under by approximately 4.5%, 1.1%, and 1.1% respectively. Is that cause for concern?

    How else should I be determining if my power supply is "right-sized" for my PC and video card, or am I perhaps barking up the wrong tree?


    UPDATE:

    I purchased a new power supply: a 950W Enermax (providing me with more than enough power for even what will come next in my PC :-) The new voltage readings in my BIOS are now:

    3.3V    3.236V
    5V      4.992V
    12V     12.096V
    

    These are much closer to the ideals than the previous power supply.

    Did this solve my problem? Well, no. :-/ So, now I'm suspecting the video card is at fault. The last time after it blanked out and I rebooted right away, I got a message on screen before POST telling me that I need to plug the power extension cable into the video card. It was plugged in.

    So, I'm thinking the video card is at fault and periodically losing power due to a bad connection or what not. The video card is next on the list to replace, and now that I have a beefy power supply, I'll be getting a much better video card. :-D


  • Related Answers
  • Ignacio Vazquez-Abrams

    The supply rails have the same voltage across the entire system. Adding load will reduce it, but it will reduce it everywhere. Having said that, the 3.3V rail does seem just a bit low. 4.5% is barely within tolerances. Another problem is current, measured in amperes. If a circuit isn't getting enough current then it could cut out completely. There's usually no way to specifically measure current, short of sticking an ammeter in the way.

    What you can do is monitor the voltage on the supply rails as you use the machine, and if you see one of them drop too low (a 5% drop is considered "too low") then get a better or larger PSU.