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CPU and PSU fans turn on but then quickly turn off as does everything else

By Gearz ยท 14 replies
Jul 29, 2010
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  1. Hey all I'm new to this forum but I've built a few computers in the past but have never experienced any problems like this.

    Case: Powerspec Cooler master case
    Processor: Intel i5 750(quad core)
    Motherboard: Gigabyte H55M-UD2H
    Powersupply:OCZ 500 watt Mod X Stream-Pro

    Here are some pictures of my build and a video of what is going on.

    Video: youtube.com/watch?v=UbuFZJQnlds

    As you can see the PSU, CPU, and Case fans are turning on and the Motherboard LED lights are blinking and then they quickly turn off. I dont think its a problem with the Power Supply because I have already returned one with the same issue thinking it was defective.


    wont let me post pictures =/

    Any help is appreciated, thanks for your time!
  2. Leeky

    Leeky TS Evangelist Posts: 3,797   +116

    Does your current BIOS version support your CPU?

    Your 4 pin power connector looks to be missing.... Top right of the video 8secs in.
  3. Matthew

    Matthew TechSpot Staff Posts: 5,313   +100

    I've had the same exact issue with the same exact PSU, CPU, and a similar (P55) Gigabyte motherboard. For whatever reason, that OCZ PSU refused to play nice with my setup even though it worked fine on two other systems with a Pentium D and Pentium E5200.

    If Leeky's suggestion doesn't work (I didn't watch the video), swap out your PSU for another and I'm nearly positive it'll solve your problem.
  4. Gearz

    Gearz TS Rookie Topic Starter

    If you are reffering to the 12v connecter then it is there. Maybe some pictures will help.

    The OSZ PSU is the second one i've tried so far. Earlier I tried with a 430 watt Thermaltake PSU and I got the same result. Maybe a 3rd one will work, is so can somebody reccomend one that will work?

    Thank you for both of your responses. Here are some pictures that will hopefully assist.(Sorry I cant link them directly, it wont let me. Just copy these into your url bar.)




  5. Zilpha

    Zilpha TS Enthusiast Posts: 319

    I see what he is talking about - you are missing that 4 pin connector at the top right of the board. What does your documentation say that powers? Usually that sends extra power to the CPU.
  6. Gearz

    Gearz TS Rookie Topic Starter

    Thank You Zilpha, so in that case will I need a new motherboard? Also I think I might have a 4 pin connector. Look at this picture here img837.imageshack.us/i/dsc0312x.jpg/ is that the thing labeled ATX 12v?
  7. mailpup

    mailpup TS Special Forces Posts: 7,103   +422

    The connector is there but it's not connected to the power supply in the video or any of the pictures you linked to.

    Also, are you using motherboard standoffs? It didn't seem like it in the pictures and your symptoms are consistent with motherboard shorting due to missing standoffs.
  8. Zilpha

    Zilpha TS Enthusiast Posts: 319

    Yes, that's the connector we are talking about. Plug a free 4 pin into that and see what happens. Re-reading my post I see I wasn't very clear about what was meant - the connector needs to be plugged up to the power supply.

    Mailpup makes a good point about the standoffs. Make sure you are using those to support the motherboard.
  9. Gearz

    Gearz TS Rookie Topic Starter

    Yeah, I'm using the standoffs for the motherboard.

    The only 4 pin connector I have on my power supply is the one thats really close to the 20 pin connector:


    and that is too close to it to reach all the way accross the mother board.
  10. Leeky

    Leeky TS Evangelist Posts: 3,797   +116

    The last picture clearly shows its not connected, unless you removed it to take the picture?

    Ref your last picture (above this post): You need the connector fitted to that AND the 4 pin connector fitted in the top right of the board as well.

    Sorry to you Gearz, I could have been much clearer. What I meant is there is no plug fitted from the PSU to the 4 pin ATX connector on the motherboard.
  11. Zilpha

    Zilpha TS Enthusiast Posts: 319

    You don't want to use that one anyway, since that is probably part of the "24-pin" main power connector. You might need a power supply with more connections on it. I have a 750w Coolermaster supply that has a handful of those little 4's.

    If you are using standoffs, and you have had the issue with two power supplies, I would wager that the motherboard is shutting itself back down because of lack of sufficient power to the CPU: meaning - you need another power connector for that little nub.
  12. Gearz

    Gearz TS Rookie Topic Starter

    Ah I see, thankyou. I'll go exchange my powersupply for one with one of those and post my results here!
  13. mailpup

    mailpup TS Special Forces Posts: 7,103   +422

    That is not likely the one. That 4 pin connector is to be used with 24 pin motherboards and is not the same as the ATX 12V.

    All modern power supplies have this ATX 12V power connector. Many even label it ATX 12V (P4) so as not to confuse it with the 20 + 4 pin connectors. Take another look. I'm sure you overlooked it.

    Edit: I looked up the specs on your power supply and it does indeed come with an ATX 12V connector. According to the picture I saw on Newegg, it has yellow and black wires going to it.
  14. Gearz

    Gearz TS Rookie Topic Starter

    Thank you everyone who helped! Turns out when I was installing the power supply, I shoved the 4pin 12v connector under a frame in the case and I forgot about it :) Its working fine now, thanks a ton!
  15. Leeky

    Leeky TS Evangelist Posts: 3,797   +116

    Glad you sorted it. Nothing worse than building a computer and then it not starting up first time. I've been there and done that! lol.

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