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CPU Fan issues. Computer does not boot up

Discussion in 'Hardware' started by marcos77, Feb 8, 2011.

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  1. marcos77

    marcos77 Thread Starter

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    Hi. I have a Dell dimension 8400. When i turn it on the cpu cooling fan comes on and sounds like it wants to take off. Nothing else happens. The monitor stays black. The power LED is steady yellow/amber, the CPU fan spooled up to hyperspeed, no HD activity or video output, and the 4 status LED's on the back of the case did not light up at all.

    Here are the steps I have taken so far:

    Yesterday I completely unplug every cable and card from the motherboard, including the heat sink and CPU processor. I plug everything back in but that didn't fix it.

    Next I decided to swap processors between my two Dell computers. Same result. Didn't work.

    I also replaced the Power Supply, memory (RAM) and hard drive but that also didn't solve the issue.

    I checked all the capacitors and they were fine. None were bulging or leaking. No cracked motherboard or burnt areas.

    What should I try next? Should I replace the motherboard? This has been really frustrating.
     
  2. Alex Ethridge

    Alex Ethridge

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    I think you are down to either the main board or the power supply. Do you have another power supply you can try? It doesn't have to be the exact match as all that needs to be powered is the main board just to see if there is any change.

    If that produces no on-screen change, my opinion is you have a bad board.
     
  3. Paynesmanor

    Paynesmanor

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    I will throw my two cents in. Try pulling the battery for 5 mins, with the power unplugged. ( it will reset the bios). This has saved me many of times.

    Check to see that the jumpers on the back of the hard drive are correct.
    Check to see that the hard drive is properly plugged in, ( both ends of the cable. ).

    Error Beep Test,
    What does it do when you try to boot with no ram? does it beep? replace the ram and see what it does without the video card in it? does it beep?

    If it beeps with the one but not the other, then the one that it didnt beep for is the problem hardware.
     
  4. win2kpro

    win2kpro

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    Lift up the heatsink shroud (Airflow Shroud) as shown in the diagram and see if the heatsink fins are clogged with dust. If so, take a small throw away paint brush and a can of compressed air and clean the heatsink.

    http://support.dell.com/support/edocs/systems/dim8400/SM/parts.htm#wp1057570

    If the heatsink is clean and the problem continues look at the Northbridge heatsink clips as shown in the attached pic. There will either be one or two wires that go across the Northbridge that attach to either 2 or 4 "loops" (eyelets) on the board where the wire or wires connect shown by the red arrows. If there is only one wire going across the Northbridge heatsink there will be 2 "loops" (eyelets) on the board, is there are 2 wires going across the Northbridge heatsink the will be 4 "loops" (eyelets) on the board. See if any of the "loops" (eyelets) have pulled loose from the board.
     

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  5. marcos77

    marcos77 Thread Starter

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    Today I tried a different power supply from another Dell computer that I have and it didn't work. Same issue with CPU Fan spinning at hyper speed. I also checked to see that the jumpers on the back of the hard drive are correct and
    checked to see that the hard drive is properly plugged in. I also tried to boot without any Ram and it didn't beep. I replaced the Ram and then tried to boot without the video card and didn't beep as well. I also tried this with the sound card but no beep was heard with any of them. I also checked the heatsink shroud (Airflow Shroud) and there was no dust. Also, none of the "loops" (eyelets) have pulled loose from the board from the Northbridge heatsink.

    Anything else that I can test? I also tried using different Ram from one of the other Dell computers.
     
  6. Alex Ethridge

    Alex Ethridge

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    Based on what you wrote, there is nothing else. It is the board.
     
  7. Paynesmanor

    Paynesmanor

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    Yep, it would seem to be the board. You can try seeing if you can get into the bios when the computer boots. If you can Try resetting the bios settings to default. one more thing is what is the monitor hooked to, as I had it hooked to the video card, and it turned out the bios had been reset to default which was the onboard video. But thats about all I can think of...
     
  8. marcos77

    marcos77 Thread Starter

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    My monitor is connected directly to the VGA port on the video card. It's an older display that does not support DVI. I was never able to get my computer to boot again. I tried it about 20 times. Anyway I was able to find the same motherboard on eBay and purchased it for about $85. This will be my first time replacing a motherboard. I was able to remove the old board, it was fairly simple. My question is after I connect the new board do I need to do anything special or will it automatically detect everything? Also, will I need to reformat my hard drive? Thanks!
     
  9. Paynesmanor

    Paynesmanor

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    It should be straight forward, Might want to check to see that the jumpers on the mobo are in the same spots as whats on your old board.

    If the boards are the exact same then it should boot. If not then you will need to reformat, Or a repair might solve the issue..
     
  10. marcos77

    marcos77 Thread Starter

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    I just received my motherboard in the mail. Installed it and everything works great now! Boots up with no issues. Thanks everyone for the help. I really appreciate it.
     
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