Does your processor has iGPU? Are you using PCIe riser or something. I can't think anything other than your power supply is not adequate or bad PCIe riser if you have one. If you have iGPU, connect monitor to MOBO and see in device manager if everything is good. What is your OS? Share more details about build so someone can help
Greetings. Yes, we would need some more details to get a better idea what's going on here, as in what parts you specifically have, is this the first time you're trying to use your video card, etc.
In the mean time, we do have a guide with some tips and suggestions for this at https://community.microcenter.com/discussion/2850/tech-article-how-to-fix-when-your-monitor-won-t-display
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