›
This forum is in permanent archive mode. Our new active community can be found here.

Low 5V rail causing computer not to POST?

AndrewAndrew
edited March 2010 in Technology
So, I've been having issues with my computer not POSTing and I've gone through the gauntlet. Here is where I am so far:

CMOS reset: Nothing
Memory check: All good, tested externally in other computer.
Video Card: Good, tested externally in other computer.

However, when I took a multimeter to my power supply, I noticed that the 5V rail is running low (around 4.4ish v). Apart from any other issues, could this be a logical cause of a non-posting computer?

Comments

  • RymRym
    Yeap. Try disconnecting nonessential devices (USB header connections, etc...) and see if that fixes it. Or, swap out the PSU and test. Low voltage can prevent POST.
  • AndrewAndrew
    I've already replaced my PSU. Works like a charm now.
  • AprecheApreche
    I've already replaced my PSU. Works like a charm now.
    Told you that was the problem.

    People, do not buy those weird gaming PSUs that are all funky. They are not reliable. Also, don't get insanely high wattages, those are mostly just to trick you. I suggest you get a PSU made by Seasonic, as they are the quality. Antec EartWatts is also actually a Seasonic, it's what I have, and it is great. Also, I have recently discovered that the Nexus brand of PSU is very good, and is super quiet. I have one in my HTPC.

    Still, even in those brands, don't bother with the insane wattages. Nexus Value 430, EarthWatts 500, these are powerful enough for almost everybody.
  • AndrewAndrew
    edited April 2010
    I've already replaced my PSU. Works like a charm now.
    Told you that was the problem.
    This thread was started two weeks ago.

    Anyways, I picked up an Antec NeoPower 650 modular PSU.
    Post edited by Andrew on
  • OmnutiaOmnutia
    Really strange problem here relating to power supplies.
    PSU that came with this system, and two other one's I've bought since, all fail to boot the motherboard even after I've taken everything out of it.
    Original is 305w, the two newer ones are 400w each.
    All three, when plugged into a PSU tester, come up with their -5v rail not working. I even tested one of them before attaching it to the computer.
    If I plug in my main computer's 500w PSU, computer boots straight away. It also lights all the test lights.

    Is it a case of a very picky motherboard or am I just some bizarre outlier, getting two duff PSUs with the same problem?
Sign In or Register to comment.