Question X570 Phantom Gaming X top PCIe not working?

57Stew

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Jul 19, 2009
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I have an Asrock X570 Phantom Gaming X with 3900x CPU installed and G.SKILL, Series Trident Z Neo F4-3600C18D-32GTZN . I have not bought a new GPU yet so put in an old MSI MD Radeon HD 7770. It would not disply. I moved it to the second slot and it posted. I installed windows 10 then updated the bios and drivers. I shut down and moved the GPU back to the first slot but no display. You could hear the pc boot though. I moved it back down and it works fine.

Is there a MB problem or a setting I missed? I won't have a new GPU until after the first of the year so would like to know if I need to RMA.