TechSpot

power comeson for 1/2 second then off again

By venger417
Jan 7, 2007
  1. i have a p5LD2 MOBO.
    i built my computer back in june 2006 and it has worked perfect until now. sometime while i was sleeping the computer went off. I hit the power button and nothing... so i turned the powersupply off in the back and turned it back on. after resetting thepower supply the computer turns on for about half a second (leds come on, fanspins) then it goes back off. it will not do that again until i turn the power supply off and back on again. the power light on mother board is ON. i figured the power supply went out so i put in a brand new power supply that i happened to have in my closet. it is still doing the same thing,i have check and doublechecked that all connections are are good. the MB is not touching the case and i have tried plugging one of my system fans into the MB CPU fan connecter. that doesnt help either.i would assume that if it was a problem with anything but the MB itself that the power would atleast stay on and beep or let me into the bios.
    other harware that i have connected: x1800 video, 2 sata2 drives in raid 0, 2x 1gig ocz memory, MB is asus p5ld2 with a pentium D 3.4GHZ 6 months old. there have been 3 or 4 times duringthe past 6 months that my computer has gone off and i had to reset the power supply b4 i could boot it back up.. any help would be greatly appreciated

    ********UPDATE 1/11/07 BIG PROBLEMS**********

    ok huge problem here.. i bought a brand new motherboard (ga-965g-ds3) cpu( c2d e6600) and case....and im havin the SAME problem as b4....i hit the power button, and the computer gets power for a SPLIT second then NOTHING...doesnt even beep! this board has built in video so i didnt put my old one VC in yet.. only thing the same is power supply, ram, cpu heatsink, and hard drives.
    here are the stepsi tookto troubleshoot it.
    1)removed hard drives and turned it on, nothing..
    2)changed power supply back to the original one from my other computer (i replaced it on my other computer that was doing this from my first post)nothing...
    3) removed the ram completely, still no power
    4) unplugged cpu fan and plugged in a different fan..notta...


    24pin MOBOpower and 4pin cpu power is connected...
    not that it matters but i was also using a different keyboard and mouse,but once it came on and went back off again i noticed that the optical mouse was still lit up...
     
  2. nismo91

    nismo91 TS Guru Posts: 1,003   +11

    hmm have you check your power supply amperage?
    It sounds like your power supply *not strong enough* to power your PC.
    If you have a sitting PSU, u might try that one also.

    btw watts in power supply doesn't guarantee you that it's good in performance.
    To check the amperage, open the case, see the A under +12V rail otherwise take a pic of it.

    welcome to techspot:)
     
  3. Nodsu

    Nodsu TS Rookie Posts: 9,431

    Isn't that normal behavious? I have seen many computers that spin their fans for a moment when you connect power (they do not turn on, you need to press the power button for that) and motherboards that simply indicate that they are powered (but not turned on).

    Maybe try pressing your power button ater turning on the PSU? :p
     
  4. Jesse_hz

    Jesse_hz TS Maniac Posts: 638

    If two different PSUs produce the same result (fan spins for a sec when you press the on button), then I would guess that either the motherboard battery is dead or the motherboard is dead. Try to replace the small round lithium battery on the motherboard.

    Hope it helps :)
     
  5. venger417

    venger417 TS Rookie Topic Starter Posts: 24

    maybe my description wasnt clear. the 1/2 second of power does not happen until i press the power button on the case. After i do that once, i will not get the 1/2 secondofpower again until i turn the power supply off and then on again, then press the power button on the case. thepower led on the MOBO stays lit even after the power failure. i know that is just an indicator that the MOBO is powered and that its not "on"


    and i will try the battery, but would a dead battery actually cause the computer to not power on at all? ive never hada battery go bad in a computer b4 so not sure.
     
  6. Jesse_hz

    Jesse_hz TS Maniac Posts: 638

    Yes, a dead battery could cause a motherboard to not boot.
    --
    Edit: I said it could cause a mobo to not boot, usually it's something else though.
     
  7. venger417

    venger417 TS Rookie Topic Starter Posts: 24

    tried the new battery, noluck. i guess themotherboard decided to die...
     
  8. Rik

    Rik Banned Posts: 4,985

    That is definitely a possibility, one thing you could do as a test is to remove everything from the motherboard apart from processor, PSU, keyboard, graphics card, and power switch and see if it will bleep with no RAM in it!
    If it does bleep it could mean that your motherboard is actually okay.
     
  9. venger417

    venger417 TS Rookie Topic Starter Posts: 24

    havin big problems.. please read my edit from the first post
     
  10. Ressurrector

    Ressurrector TS Rookie Posts: 45

    hmm I have seen this problem before.........your pc is not starting because something in it has failed. my advice would be to remove all unecessary cards leaving only bare essenstials to boot up.....I think bad cards can do what you have described but don't hold me to it I have the answer to this but its been awhile..... tell us how it goes
     
  11. Ressurrector

    Ressurrector TS Rookie Posts: 45


    strange thought this just caused a clock that couldn't keep time and reseted after every reboot
     
     
  12. venger417

    venger417 TS Rookie Topic Starter Posts: 24

    yes i tried that, i took out everything except the new components. (the mobo and cpu) same power supplies because i dont have anymore new ones. does the same thing with just the brand new motherboard powered. would a bad component such as ram or video card shortout the motherboard?
    is it possible that whichever causd the original problem permanently damaged my new one?
    even with nothing but the MOBO plugged in it should at least stay powered and beep at me...
     
  13. jakegerome

    jakegerome TS Rookie

    I didn't bother with reading all of this post, but im guessing no one told you to try and new power cord or outlet. I have seen this before with my brothers computer, turned out his power cord had went bad.
     
  14. Tedster

    Tedster Techspot old timer..... Posts: 10,074   +13

    did you plug in BOTH the CPU and mobo power?
     
  15. venger417

    venger417 TS Rookie Topic Starter Posts: 24

    yes i tried a different cord from the PSU to the wall also used a different outlet in a different room (no surge protector) while i was working on it.

    and yes the 4 pin cpu and the 24 pin MOBO connectors were connected.

    im going to test both PSU today, i think maybe old MOBO shorted which in return shorted out PSU then did same thing to the new PSU that i installed and then transfered to new system..


    ive found several other forums wherepeople have posted about the same problem andnone have had final solutions
     
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