Unable to get PCIE slots working

Discussion in 'Asus' started by Tech123, Jan 24, 2025.

  1. Tech123

    Tech123

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    Hi all,

    I have an ASUS P8Z77-V LE PLUS motherboard, which I have been using for years with an i5-2300 CPU and an ASUS HD 5450 GPU connected to the PCIE x16_3 slot (black). This setup was working fine, up until I found that the GPU would be insufficient for 1080p video playback. This is where the problems started.

    I removed the HD 5450 and plugged in an HD 5850 into the PCIE x16_2 slot (white) because the card would not fit properly into the _3 black slot, since the slot is at the end of the motherboard and doesn't provide enough room for a modern GPU to fit into. On boot, the result was a black screen. By disconnecting the video cable from the GPU and plugging into the iGPU, I got a display immediately, so I started poking around in the BIOS.

    I set the GPU settings to use PCIE by default, and rebooted. The result was the same black screen. Next, I tried changing the speed from x2 mode to x4 mode on the black PCIE slot --- just to see if it would make any difference, which it did not, so I set it back to x2. Next, I shutdown the PC, and then tried moving the HD 5850 to the PCIE x16_1 slot (blue), rebooted, same result. Next, I shutdown and tried the HD 5450 in both the white and blue slots, and that card was not detected in those slots either.

    I asked around and was suggested to try a different CPU, so I did. I installed an i7 2600k. Same results.

    I also noted that whenever I set the GPU mode to PCIE in the BIOS and reboot, it switches back to "Auto".

    So to summarize, my underlying issue is that I cannot get a GPU to be detected in the white or blue PCIE slots.

    Based on my testing:

    - The GPUs are not the issue, since they work fine on other systems
    - The CPUs do not seem to be the issue --- based on my reasoning that it is very unlikely that I have 2 defective CPUs. Unfortunately, I don't have another LGA1155 motherboard to test with.
    - The PSU is not the issue, since it is brand new and provides more than adequate power.

    I am leaning towards either a BIOS setting, an onboard switch/jumper setting, or defective PCIE slots --- but could use some feedback to help with working through this.

    Thank you for reading and thanks for the help in advance :).
     
    Tech123, Jan 24, 2025
    #1
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