Changed psu computer wont start now

By arran ยท 11 replies
Feb 28, 2008
  1. i bought an antec 650W neopower blue to replace a crappy icute 350w power supply i connected it up and my computer started up fine. then i changed my cpu fan to a zalman flower cooler it then started fine again, but after tighting up all of the screws and closing my case up and starting it up agian my computer doesnt start. there is power to all of the parts as the case fans,drives ,cpu fan, motherboard light are all on, the lights on the front of the case for when you power on the system dont come on thought not sure why. so basically everything appears to be running but i dont get anything on my screen and case lights done turn on, my screen is still working by connecting it up to my laptop so that isnt a problem. i have already tried putting my old power supply back in just to be sure and didnt make a differance.

    Please help aint got a clue what is wrong!!!!!
  2. kimsland

    kimsland Ex-TechSpotter Posts: 14,523

    Hmm can you just swap that fan back too, as a test

    arran, I can't believe this. I do feel for you, you finally got a new PSU and now this !
  3. arran

    arran TS Rookie Topic Starter Posts: 51

    thanks lol you always seem to be the one helping i am going to trying changing the fan back later
  4. arran

    arran TS Rookie Topic Starter Posts: 51

    thanks it worked i have no clue why changing my fan caused a problem
  5. kimsland

    kimsland Ex-TechSpotter Posts: 14,523

    The fan has either the wrong power rating, or wrong pin layout.
    Although I helped you in minutes, when I first had the same fault, it took me two (full) days to work out why my new computer wouldn't start.

    So, is everything now OK ?
  6. arran

    arran TS Rookie Topic Starter Posts: 51

    well i seem to be struck by bad luck because after i got it working and started up i realised one of my case fan control leads was stuck behind the back of my motherboard so i went to take off my motherboard and one of the screws just spins so i can take the motherboard of so i undid all the rest and tried sliding the backplate of for my fan so i could get the lead out ,but when i went to put the plate back on one of the pegs seems to have broken so i need to get a new backplate!!!!

    it would be useful if i could just use the new fan its a:

    Zalman CNPS7000B-CU Super Flower Socket 478, 754, 940, 462 & 939 CPU Cooler

    that is a link that has the specs any clue why this might not work. the cpu fan connection on my motherboard seems fine and the fan does start my computer just doesnt seem too!!

    i have been reading throught zalman and its states that if the rotation of the fan is too slow the motherboard may not boot, i didnt connect up the fan mate when i first tried so i could try attaching it this time and turning the rotation to full and see if it boots. if you have any other ideas they would be more then welcome,as i have no clue if this will help.
  7. kimsland

    kimsland Ex-TechSpotter Posts: 14,523

    I have no idea what your mobo gives out on the fan plug (you could test with a meter, but up to you!)

    As for the backing plate, what broke exactly, I know we're talking about proper earthing, but just put it together (with the plate too)

    Put the old fan on it
    New PSU fitted

    And turn it on
  8. arran

    arran TS Rookie Topic Starter Posts: 51

    the bit you screw into on the back plate which is a small peg has broken of, i can push it back in but the fan doesnt hold down when my case is vertical but i could probally use it laying down.

    do you i just check the output pin on the fan supply with a meter then too see the output.
  9. kimsland

    kimsland Ex-TechSpotter Posts: 14,523

    arran you're truly going to be the most knowledgeable member asking for help (on many threads- I've noticed) there has ever been!

    If you want to test the Voltage, you decide! The concern is, hurting the presently working board.

    The Motherboard plate I still don't get (strangely) There is no screw (or thread) on there.

    Are you speaking about the HeatSink assembly (for the CPU)
    If so, depending on the design, these corner feet, can come loose, and can be easily re-fitted
  10. arran

    arran TS Rookie Topic Starter Posts: 51

    i am talking about he plate you fit on the back of the motherboard so you can attach the fan or heatsink what ever you happen to be using on top of the cpu to disperse the heat from the cpu.
  11. kimsland

    kimsland Ex-TechSpotter Posts: 14,523

    This thing (HEATSINK RETENTION Module Adapter Bracket)


    Oh that: (Thermalright Backplate for AMD K8 Socket 939 and 940 processors)

    Yes that looks important !!
  12. arran

    arran TS Rookie Topic Starter Posts: 51

    this is the bit the fan sits on with cpu below


    and this link goes to more or less what the back plate looks like

    one of those two pegs is what has broken of

    yer i cant really attach the fan without it coz it just hangs so not going to cool the cpu which is a major problem. i will just order a new one today

    thanks for your help not much i can do till that comes.
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