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    Desktop PC Startup Problem

    Just finished setting up my pc in a new case and everytime i boot up almost immediately it will turn off, a few seconds later just back on, and then off and then on etc.

    Seems like a short to me, can't seem to work out where the problem is coming from. Anyone have any ideas what it might be???

    23 Comments

    The connection that the power cable goes into.

    check the pins are secure and the cable going into it is secure.

    Don't really know any mega technical stuff you could check, good luck though.

    PSU plugged into MB properly and 12v rail for CPU

    CPU not over heating and cutting out

    Could be heat issue.

    You seated the processor right? is the Processor fan running?

    Not been OC'ing have you ?

    Check the screw points on the mother board, might be causing a short, although I wouldn't expect it to start up at all....or only once and then let the magic smoke out!

    Original Poster

    oooh, will try those, talking bout the PSU plugged in i have one of those stupid 20 pin, and then a separate 4 pin that has to go into to the main 24 pin, will make sure those are seated properly, here we go again

    Another thing it could possibly be, if its not heat related is literally the power is staying on, in an ATX Powered Mobo if a maintained positive & negative feed on the header board is maintained it will power on then shut down a few second later.

    Check your header board, ensure the leads from the power button of your case are correctly polarised, and also check you have not got a "sticky" power button on the case.

    cicobuff;7672698

    Another thing it could possibly be, if its not heat related is literally … Another thing it could possibly be, if its not heat related is literally the power is staying on, in an ATX Powered Mobo if a maintained positive & negative feed on the header board is maintained it will power on then shut down a few second later. Check your header board, ensure the leads from the power button of your case are correctly polarised, and also check you have not got a "sticky" power button on the case.



    Good point check your power switch and reset switch jumpers!

    Celticsun;7672729

    Good point check your power switch and reset switch jumpers!



    Yeah, sometimes its easier to actually fear the worst when it could be something much simpler! Lets hope it is.

    Original Poster

    OK i am now using an adaptor for the 24 pin mobo connection

    ive swapped round the power and reset switches

    removed the gfx card and now removed the ram modules but all lead to the same result. Time to dwell even further

    khy86;7672845

    OK i am now using an adaptor for the 24 pin mobo connectionive swapped … OK i am now using an adaptor for the 24 pin mobo connectionive swapped round the power and reset switchesremoved the gfx card and now removed the ram modules but all lead to the same result. Time to dwell even further



    When you have the ram and GFX card in, and it powers up, does the computer actually POST before shutting down (ie bleep and you get the bios info onscreen on your monitor)?

    khy86;7672845

    OK i am now using an adaptor for the 24 pin mobo connectionive swapped … OK i am now using an adaptor for the 24 pin mobo connectionive swapped round the power and reset switchesremoved the gfx card and now removed the ram modules but all lead to the same result. Time to dwell even further



    Have you checked that the CPU cooler hasnt been dislodged ?.
    Just reread OP are you saying it turns itself off and then turns itself on again ?.

    Original Poster

    CPU cooler spins so it turns on, no information comes up regarding the BIOS, im going to remove everything and just try to see if it can stay on.

    Yup the computer turns off and then and again itself. Once ive switched the PSU off it still attempts again but obviously no power so it can't, its stuck in sort of an infinate loop

    Take the battery out of the mobo and unplug the power pack and see how you go.

    khy86;7672998

    CPU cooler spins so it turns on, no information comes up regarding the … CPU cooler spins so it turns on, no information comes up regarding the BIOS, im going to remove everything and just try to see if it can stay on.Yup the computer turns off and then and again itself. Once ive switched the PSU off it still attempts again but obviously no power so it can't, its stuck in sort of an infinate loop



    Sounds like a dodgy power switch or is there aposibiltiy its connected wrong .You could try disconnecting the power switch and just use a small screwdriver to touch the + and - power pins together to test it

    khy86;7672998

    CPU cooler spins so it turns on, no information comes up regarding the … CPU cooler spins so it turns on, no information comes up regarding the BIOS, im going to remove everything and just try to see if it can stay on.Yup the computer turns off and then and again itself. Once ive switched the PSU off it still attempts again but obviously no power so it can't, its stuck in sort of an infinate loop



    If bios doesnt show, then there definitely is a problem elsewhere, check that your CPU is correctly seated in its socket, reseat if necessary, and ensure RAM is seated properly in their sockets. Ensure that the graphics card is properly seated, and if external power is needed from the PSU that you have it plugged in.

    Also as Adam2050 said, its a great idea as well to clear any residual electricity from the PSU by unplugging the kettle lead for a few seconds, as well as taking the CMOS battery out of the motherboard for a few seconds. Then reconnecting.

    Original Poster

    OK reseated CPU, replaced CMOS battery with a conveniently placed brand new one right next to me, checked connections and am now down to the barebone with only the 2 relevant connections in place and same result.

    Now i am going to try one of my other 4 PSU's to see if thats the problem

    Ahhh I got it.

    Nothing to do with that.

    You have fused the mobo to the case. You need to make sure there is no metal touching the case, done this various times, use the spacers provided to stop the case fusing to the mobo.

    Creating a circuit so the PSU knocks itself off you will find it does the same thing with the other psu or might not dependant on its age.

    Try the mobo outside of the case. Bet it works with the new psu.

    cicobuff;7673036

    If bios doesnt show, then there definitely is a problem elsewhere,



    The graphics card has to boot up before the main system Bios and these days they generally don't show it so check that as well (has it got any external power connections? If so then try some different ones if possible).

    Also, with the power switch did you check the pins in the manual?

    If you have a correctly seated CPU, with a heatsink and fan in place and connected to the motherboard, just one stick of ram correctly seated, and the graphics card correctly seated (and if necessary external power from the PSU) and it doesn't POST showing the system BIOS, then there definitely is a problem either a faulty component, the motherboard is shorting, PSU problem, jumper setting problem, or as stated something to do with the header connection from the power button.

    Original Poster

    woooohoooo we have BIOS settings showing, with the new PSU and after reseating everything, will now go back to old PSU to see if i can rule that as the culprit. Hopefully i can keep it going, i did also remove a slightly bent screw from the mobo just incase that was shorting, trial and error now

    Rep for Everyone :-D

    khy86;7673397

    woooohoooo we have BIOS settings showing, with the new PSU and after … woooohoooo we have BIOS settings showing, with the new PSU and after reseating everything, will now go back to old PSU to see if i can rule that as the culprit. Hopefully i can keep it going, i did also remove a slightly bent screw from the mobo just incase that was shorting, trial and error nowRep for Everyone :-D



    As I said that will be the culprit.:whistling:

    Original Poster

    ahahaha you could be right, the old PSU is now working which is a good thing as its the good one, there is also still another bent screw which will be swiftly removed but alas, 2 hours of problem solving is sorted.

    Will now remove EVERYTHING and reseat it all properly, also my 4850 just arrived, which doesn't look like its going to fit grrrr.

    khy86;7673469

    ahahaha you could be right, the old PSU is now working which is a good … ahahaha you could be right, the old PSU is now working which is a good thing as its the good one, there is also still another bent screw which will be swiftly removed but alas, 2 hours of problem solving is sorted.Will now remove EVERYTHING and reseat it all properly, also my 4850 just arrived, which doesn't look like its going to fit grrrr.



    Case to small?

    If so don't fret.:w00t:

    Original Poster

    case is too small, and just received it today.

    My Cosmos case is big, but the PSU is too small, and now this case is too small but the PSU fits.

    Never realised how complicated these things can get, and ive got my watercooling kit coming soon aswell, this is gonna be hard lol
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