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Solved: Motherboard will not detect graphics cards

Discussion in 'Hardware' started by Santana, Nov 30, 2014.

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  1. Santana

    Santana Thread Starter

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    So, I had a power outage and my PC wouldn't start up afterward. I took it to a computer repair shop and they determined it was the motherboard. I replaced the motherboard now, installed Windows 7 again (but kept the old files on the HDD, as custom install lets you do, it just partitions the drive), and only the on board graphics is working. I can't get my PC to detect any graphics card despite plugging them into the PCIe x16 slot (closest to the CPU) and their fans coming on. There is no indication of a graphics card in Device Manager.
    Things I have tried:
    -Updating BIOS
    -Installing most recent chipset drivers
    -two different graphics cards (560 Ti and 6850)
    -updating Windows, including all optional updates
    -Going into the BIOS, selecting primary display as PEG (which is the PCIe slot), it saves, I plug in a monitor to my GPU, nothing, but I plug the monitor into the on-board graphics and it works. The option for primary display is reset in the BIOS back to "Auto select" after this.
    -Tried the PCIe x4 slot, it doesn't detect them
    -I tried installing Nvidia/ATI drivers, but they won't even install because I don't have the proper hardware (card not detected)

    I'm not sure what to do now... I don't think the slots are dead because neither PCIe slot works. Am I missing some sort of motherboard software or is it a compatibility issue? I'm really at a loss here.

    Specs:
    Windows 7
    4 GB DDR3 RAM
    Motherboard: Gigabyte GA-B75M-D3H
    PSU: Corsair GS600
    CPU: i5-2500k
    GPUs: EVGA GTX 560 Ti and MSI Radeon 6850

    EDIT: I haven't tried disabling on-board graphics yet (just made sure PCIe was the priority), because if that doesn't fix it, then I won't have any display and will have to reset the mobo (last resort).
     
  2. managed

    managed Trusted Advisor

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    I think you should bite the bullet and clear the Bios/Cmos to see if that helps.
     
  3. dustyjay

    dustyjay

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    It is possible that the same thing that killed the motherboard may have also killed the video cards
     
  4. saikee

    saikee

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    Have you tried to disable the onboard graphic facility?
     
  5. Santana

    Santana Thread Starter

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    No, not possible.

    Well, I mentioned that in the edit. It's a last option because then I might end up with no display.
     
  6. saikee

    saikee

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    Others may give a better explanation but I believe the mobo can only drive a one set of graphic display at a time. Multiple displays arer possible within one graphic card if it has that function as most expensive cards got it. If an onboard graphic and a plug in graphic card are offered to a mobo it must make a decision to send the signal to one device.
     
  7. Santana

    Santana Thread Starter

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    I guess I can give it a shot. I've never cleared a CMOS before, but it seems easy enough and I'm really out of options.

    Shouldn't the GPU at least show up in Device Manager, though, even with on-board going?
     
  8. saikee

    saikee

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    That I don't know.

    However if the mobo cannot send graphic signal to every graphic card plugged in by a user and must decide to send the signal to only one device then the Device Manager should not report the unused hardware because the BIOS would not hand that information to the OS.

    If you see the device in the Device Manager that means you should be able to use it.

    Multiple displays are embedded function of a good quality graphic card that can handle and configure the monitors plugged to it. That is based one one signal source.

    I just don't think a mobo is ready or clever enough to manage one grahic signal for two different hardware because the combinations (screen definition, vertical frerquency, horizontal frequency, colour etc) could be impossible to cope but I could be wrong. The minimum function of any multiple display is the display can be a repeat of each other or an extention of the other.

    I have several mobo that have onboard graphic but I always added a better one in each. I think modern mobo can sense the port and select it for display. Thus your question should be if a mobo has selected one graphic card device to communicate with a user could it still make use of another grahic device ?

    This web page suggests the onboard graphic card should be disabled in the Device Manager.
     
  9. closetvibes

    closetvibes

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  10. Santana

    Santana Thread Starter

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    I've read the motherboard manual, but I didn't see anything in there that would solve this.

    Anyway, I went ahead and disabled the integrated graphics in device manager, then disabled them in the BIOS, then I set the primary display to PEG. I connected up my monitor to the card and booted. The POST was a long beep followed by 2 short beeps, which I believe means the motherboard has no display to connect to. So, that solution didn't work.
     
  11. 88tarot88

    88tarot88

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    same power supply as when you ahd the outage?
    try swapping that or
    grab a pcie power adapter and throw them on a couple of molex plugs and try that.
    to me it looks like a power issue
     
  12. Santana

    Santana Thread Starter

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    Yea, same PSU. The PC works fine otherwise and the fans come on for both GPUs, so could that be a power issue still? I'll try another PSU tomorrow or something.
     
  13. 88tarot88

    88tarot88

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    check the box your video cards came in most come with a molex/pcie splitter.
    fans only require X power, the pcie slot will provide some of the power but most bigger video cards needs extra.
     
  14. Santana

    Santana Thread Starter

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    Turns out both of the graphics cards I was testing were dead!
     
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