TechSpot

PSU? Motherboard?

By dbonniwell
Dec 1, 2012
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  1. 10 days ago, When I press the button to boot up my computer and the compter lights inside the unit flash on momentarly as do the cooling fans and shuts right off. Less than a second.

    5 days ago I pressed the button again and the computer booted up and ran normally.

    Today it was back to flashing on and turning right off. I can hold the button in and it does this in succession on off on off etc.

    I took out the sound card video card and unplugged everything that draws power except the CPU and the same thing on, then off within 1 second

    Motherboard is a 790i by EVGA
    PSU is Silverstone OP850 Watt
    This unit is not that old, not that many hours on the build.
    Any ideas?
     
  2. Tmagic650

    Tmagic650 TS Ambassador Posts: 20,942   +167

    Power supplies are easier to replace than motherboards. Try this first...
     
  3. dbonniwell

    dbonniwell TS Enthusiast Topic Starter Posts: 145

    I pulled the powersupply and put it on another computer and it worked fine
    Now could it be the MB or the off on switch itself. I would like to test that switch by rigging up another to see if that works, if the same problem, then do they sell plug in on off switches?
     
  4. Tmagic650

    Tmagic650 TS Ambassador Posts: 20,942   +167

    The switch is a momentary contact kind of switch, as long as you can connect it to the motherboard header you should be okay. You can test the motherboard by shorting the pins where the old switch connects to the motherboard. Just touch the pins with a small screwdriver and quickly release. If the motherboard starts up, the switch is bad. If it doesn't start up the motherboard is bad
     
  5. mailpup

    mailpup TS Special Forces Posts: 8,462   +229

    Another way to test the switch is to "switch" the wire leads with the Reset button. They both work the same. Use that as a spare button to test with.
     
  6. Tmagic650

    Tmagic650 TS Ambassador Posts: 20,942   +167

    Yes, I forgot that one :)
     
  7. dbonniwell

    dbonniwell TS Enthusiast Topic Starter Posts: 145

    Sincere thanks for your help,
    I shall do so, I also found a button on the MB itself and can try that too. Sorry I did not know this button existed till now
    I will report back the results
    Now I sit here thinking "Now why didn't I think of that" about the switch
     
  8. dbonniwell

    dbonniwell TS Enthusiast Topic Starter Posts: 145

    I plugged in the reset switch to the start switch post and while I was puting it back together I would plug in one thing and try plug in another and try till I had it fully assembled and it worked that day.
    then the next day, same problem. EVGA told me to ake the mother board off completely and put on card board or wood and try. I already had it down to near barebones as you can get and it happened. Any other thoughts out there?
     
  9. Tmagic650

    Tmagic650 TS Ambassador Posts: 20,942   +167

    It has to be the motherboard
     
  10. dbonniwell

    dbonniwell TS Enthusiast Topic Starter Posts: 145

    Thoughts exactly, Now to convince EVGA. Thanks for your assistance, Disregard the line through my typed words
     
  11. Shiney

    Shiney TS Enthusiast Posts: 223

    Try resetting the bios, check cmos battery
     
     
  12. dbonniwell

    dbonniwell TS Enthusiast Topic Starter Posts: 145

    Thanks for your reply
    Actually the thing will start up today. Not sure about tomorrow though and the machine never moves
    I checked the battery with a volt meter and it was at 3 volts and I reset the CMOS
    How often are those batteries changed out? I have had this thing run just fine for over 4 years now
     
  13. Tmagic650

    Tmagic650 TS Ambassador Posts: 20,942   +167

    CMOS batteries can last between 1 and 6 years... or longer
     


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