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Computer turns ons runs for second and powers down

Discussion in 'Motherboards & Memory' started by cor3640, Jan 3, 2008.

  1. cor3640 New Member

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    Hi,
    About 2 weeks ago my computer was shut down and when I started it back up the power came on and would stay on but nothing would happen, I tried to run barebones and no difference. I RMA'd both the MB and processor. I have both of the new ones I have put them together and when I hit the power switch it starts for like 1/2 sec and powers down, before I can power it up again I need to shut the power supple down for a few seconds. Let me start by saying that I'm running the board outside the case to eliminate any grounding issues, im also running with just the MB, processor, and power switch attached to the PC, I have tried another power supply that I know is good and thats not working either, same effect. Is it possible I have another bad MB ? Maybe the powersupple with run another pc but not this one ? Im running barebones so there shouldn't be to much draw on the powersupply right ? Also I had this setup running for about 1.5 years with no problem untill I just RMA'd the parts... Please Help ! corey.r@verizon.net :shadedshu
     
  2. Hawk1 New Member

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    Need some details. Fill out the system spec's in the user CP. What MB/CPU are you working with? What PSU's did you try. What GFX card? Where outside the case are you running the setup (wood/plastic table etc.) What cooler on the CPU?
     
  3. newtekie1

    newtekie1 Semi-Retired Folder

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    The cooler might not be seated correctly. Also, make sure the RAM you are using is good.
     
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  4. tzitzibp

    tzitzibp

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    I agree. Be specific, there are many here that can help, but they all need information about your hardware and maybe a couple of pictures of your current layout...:cool:
     
  5. panchoman

    panchoman Sold my stars!

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    if you rma'd the cpu & the motherboard, and the problem persists. chances are.. either your motherboard is getting shorted by the case, or most likely its your psu.
     
  6. t_ski

    t_ski Former Staff

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    Even if you are running limited hardware, make sure you have a CPU heatsink installed with the fan plugged into the header, and use one stick of memory and a video card. Also, with some motherboards, there are multiple connectors for the power supply. Make sure all these are plugged in, not just the 20/24 pin main connector from the power supply.
     
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  7. cor3640 New Member

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    I added the system specs

    I have tried running with nothing but CPU board and power attached and nothing, I have also run with ram and video in there and I get the same effect, is it possible that the fan supplied with my new processor is bad ? Also when you talk about the seating being correct do you mean just clipped down? it only goes in one way as far as I can see. All these componets were running fine before but after RMA I cant get the PC to stay powered up. When I say im running it outside the case its on a peice of cardboard with an anti static bag in between the two. One thing I also noticed is that if I unplug the 4 pin connecter I get the same results, does this mean anything ? I have tried another powersupply with the same effect and the ram is running with no problems in another machine. Is it possible that this power supply is bad and I fried the new motherboard ? HELP =)
     
  8. t_ski

    t_ski Former Staff

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    By seating the heastsink, yes, it should be clipped down tight. If you are running the CPU without a heatsink it is possible to fry it. The fan needs to be plugged in, because some boards don't like it when there isn't a CPU fan attached. If the fan starts to spin, it's good. If not, try hooking it up to another machine (you don't have to install it, just connect the fan to power and start the machine).

    There are a few ways to test the power supply. You could use a multimeter and check the voltages, or use a power supply tester to do the same thing. Chances are you may not have either one (although you can pick up a meter for about $10 at Sears or the hardware stores). If you don't have either, you could try using the power supply from the other PC to power this mobo and CPU. You could try to power the other PC with this power supply. Basic troubleshooting starts with running the minimal amount of usuable parts (CPU, heatsink/fan, motherboard, ram, PSU and video card). After that, you need to start swapping out parts with known working parts, or putting questionable parts in a working machine, which is what you're doing.
     
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  9. Any "Beeps"? Tried to clear CMOS [JP1] (so you perhaps could enter BIOS)?
    Make sure no standoffs are creating any short circuit (there is always 1 that shall not have a screw on it!). And how is the Hot Key Power ON [JP5] is it pins 1-2 (disabled) or pins 2-3 (enabled)? And CPU fan is connected to [FAN 1]?

    Could be like you say , that the PSU isn't "strong enough" to power up the system.

    Oh and make sure that the LED's (PWR/HDD) are correct. Don't know about your mobo, but I know if my reset connector is "turned around" I get same thing as you do right now..
     
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  10. niko084

    niko084

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    Possible you can blame is on the power supply, thats almost what it would seem, but 400 watts even a ultra cheap 400 watt that cost $25 could run that system.

    So... If you have another machine, try the other power supply. Also like said above, bios beeps, plug a speaker in if you don't already. I had a machine do this to me due to a blown northbridge in the past. But there is a decently long list of issues here so we just have to narrow them down.
     
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  11. EnglishLion

    EnglishLion New Member

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    If you need to turn off the psu in between attempts then it's overloading and kicking in the auto cut off feature. So you can rule out the BIOS not liking fans not connected etc.

    And if your using ram, video card, psu etc that's proven as working then it must be the new parts. I can't see the CPU pulling down the psu, so I would suggest it's the mobo. But be sure the other parts especially the vid card and psu are actually good.

    I have a damaged 7800GTX that does the same thing, power comes on for an instant before the psu shuts down requiring a full reset to get going again. But it's visually faulty with a burnt out component.
     
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  12. Could it not be that a "forgotten" power cable is not connected? According to the online manual of the BFG nForce4 Ultra http://www.bfgtech.com/CMDocs/BFGTech/Mobo_NF4_Ultra_manual.pdf (look at the picture of the mobo) there is one 24Pin connector and one 4Pin connector. I recall that when I first got my mobo I did not connect the 4 pin, and what happend was almost the same: Fans powered up, some beep's , power off.
    And then I looked in the manual and laughed at my own mistake...

    Oh and one more thing, and a closer look at the manual they say "...connect the 21 pin connector..."??
    What 21 pin?, the
     
    Last edited by a moderator: Jan 3, 2008
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  13. niko084

    niko084

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    I wouldn't think so, but its a possibility, so make sure everything is connected :)

    Good thinking!
     
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  14. Another question , cor3640 , what brand is your PSU? Perhaps it's just something simple to do with that??
     
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  15. cor3640 New Member

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    PSU brand

    I'll check the brand when I get back to my house, but don't you think if I had the same componets running before then it should work now ? In other words I had the exact same hardware before now im using new hardware , same parts but physically new so I shouldn't have any compatibilty problems that I didnt have before.. no ?
     
  16. Snipe343

    Snipe343

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    Same thing is happening to me but i broke itXD, i ordered new parts so you probely just have a bad board.
     
  17. True, and have you made sure all power connections are as they should be?
    Also make sure that the connections for PWR_ON , RESET , PWR_LED , HDD_LED etc.etc. is correct. Sometimes even something like that can make a difference..
     
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  18. newtekie1

    newtekie1 Semi-Retired Folder

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    I know this sounds odd, but try removing the anti-static bag. They are slightly conductive, they work by keeping the charge all around the board the same, and they have to be conductive to do that. I had a friend doing exactly what you were doing, and having the same problem. It turned out that the anti-static bag was shorting out the back of the motherboard. Once he removed the bag and placed the motherboard directly on a piece of cardboard(the motherboard box) it ran fine.
     
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  19. cor3640 New Member

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    Thanks for all the great info guys, seems that I had another bad board on the RMA, just in case I bought a new case +500w power supply installed the parts and everything is running great.... Thanks again .
     

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