Pc won't boot.

Hi there, i have a problem recently my pc suddenly stopped booting that is weird since:
1. My mobo is 2 months old
2. i didn't do any overclocking
3. Its the 4th mobo with the same problem
I suspect it has something to do with electricity.
Now the pc will start But it wont boot here are some important marks:
1. The gpu fan changes every 3 seconds from low to loud.
2. I installed overdrive the night before to change fan speed.
3. My mobo still goes on but won't boot even after i removed it and put it on wooden table and removed ram,gpu and all cables.
What should i do clear cmos?

Thanks for you're patience.

Gigabyte 990FXA D3
5 answers Last reply
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  1. I smell an rma.. return for another new one i guess..
  2. That Does not explain why 4 different mobos had ALL the same problems i didnt do anything that could Suddenly kill a 4 mobos.
  3. OK, lets start troubleshooting.

    This is basically a new build even if it is a couple of months old.

    We need complete system specs. For example, you could have a power supply killing your motherboards.

    So, first:
    just to make sure you didn't overlook something simple.

    Work systematically through our standard checklist and troubleshooting thread:
    I mean work through, not just read over it. We spent a lot of time on this. It should find most of the problems.

    The following is an expansion of my troubleshooting tips in the breadboarding link in the "Cannot boot" thread.

    Now, this is something like you did when you tried to build your system on a wooden table, but to be a useful troubleshooting technique, there are things you need to know. :)


    I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different, but they all use a single short beep for a successful POST.

    Breadboard - that will help isolate any kind of case problem you might have.

    Breadboard with just motherboard, CPU & HSF, case speaker, and PSU. Breadboard with just motherboard, CPU & HSF, case speaker, and PSU. At this point, if you do not have a system (internal case) speaker, you really need one.

    Make sure you plug the CPU power cable in. The system will not boot without it.

    I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case once you are finished.

    You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU. Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

    If no beeps, LED's, or fan activity:

    Check for line power at the PSU input. Extension cords, power strips, and power cords do fail.

    If you have power and no beeps, suspect components in likely order are PSU, motherboard, and CPU.

    Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep (a successful POST), they also do not indicate that the system is booting.

    At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

    The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

    You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.

    A way that might be easier is to use the main power plug. Working from the back of the plug where the wires come out, use a bare paperclip to short between the green wire and one of the neighboring black wires. That will do the same thing with an installed PSU. It is also an easy way to bypass a questionable case power switch.

    This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.

    If the system beeps:
    If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card.

    Silence, long single beeps, or series of short beeps indicate a problem with the memory. If you get short beeps verify that the memory is in the appropriate motherboard slots.

    Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST.
    At this point, if the system doesn't work, it's either the video card or an inadequate PSU. Or rarely - the motherboard's PCIe interface.

    Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card.
  4. specs:
    Gigabyte 990FXA D3 mobo
    ASUS EAH 6670 GPU
    FX-4100 quad core CPU
    CX600 corsair 600 watt PSU (did the same thing with a different 450 watt psu so i dont think its the psu)
    well these are the core components
    oh and one 2gb and a 4gb ram kingston ram stick
    thanks btw i will work on it and see... since mobos dont suddenly just die.
  5. oh and a 500gb western digital HDD
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