Just installed new psu now MB wont boot

Hi. I have just installed a new ,larger, psu in my PC wnich was working OK before. When I came to turn it on the fans started to turn briefly then almost immediately stopped. I went back and rechecked all the connections (including the MB 24 pin and 8 pin) and they were all correct. I then decided to put the original psu back in, but again it failed to boot with the same problem. (Fans start then immediately shut down). I decided to test the new psu by attaching it to an old motherboard that I put out on the table, without a case. I attached a monitor and the system sata drive from my main pc and switched on. The system booted normally, therefore it seems that my new psu is working OK. I wondered whether this means that either my cpu or motherboard has gone and if so how to tell which one? I take care when installinng components by using an antistatic wrist strap, but wonder if there is anything else I might have done to cause this fault. I am worried that if I buy a new MB and it is the cpu that is bad, this will then blow the new MB (and vice-versa if it is the MB bad)
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  1. Hmm it could be the cpu ats what I first suggested upon reading that you had tried the psu on another mobo. Am yea ats a tough one as it could be the mobo does any lights come on like the hdd or on/off switch
  2. Thanks for the reply ac13044. No lights on, but hdd activity light was not working before so this is not really any indication. Just for further information I should add to my original message that the old MB that I used to test the psu is not compatible with my present processor or memory types so I cant just swap the cpu onto that board to try it. I read about post (message) cards but, snce the system shuts down almost immediately I doubt whether it would be enough time to operate the error message. I have also tried removing the MB from the case and running it on the table, just as I did with the old MB to test the psu. However it still has the same problems as when it was mounted in the case. If I cant find a way to test whether it is the MB or CPU that is bad it looks as though I may have to abandon both and replace both. together.
  3. Ah Right I see could be a number of issues. Take the cpu out just leave the psu and mobo hooked up see if power comes through and stays on if you have doing this. then to me it would be either your motherboard or psu. does your psu work on your old mobo
  4. ac13044 said:
    Ah Right I see could be a number of issues. Take the cpu out just leave the psu and mobo hooked up see if power comes through and stays on if you have doing this. then to me it would be either your motherboard or psu. does your psu work on your old mobo
  5. I will try taking the cpu out. May take a couple of days before I have time. The psu does work ok with the old MB. I am not clear whether the power staying on, without the cpu, proves whether the cpu or the MB is at fault.
  6. Connected MB up again and power on - same as before. I then took the cpu out and powered on. No response at all, no fans - nothing.
  7. list down system specs and show pictures of your connections.
  8. superninja12 said:
    list down system specs and show pictures of your connections.


    Thanks for the replies but I don't think there is much point in carrying on with this problem, as there seems no way of finding out for certain if the cpu, motherboard or both have gone and have decided to invest in a new cpu and motherboard bundle. Thanks again for all the suggestions.
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