In this case, a picture is not worth 1000 words. Need detailed specs to help.
Do you have a GPU or are using CPU with integrated graphics?
Where are you plugging the monitor in on the PC? If GPU, plug into that (towards bottom or right on most cases). If not, plug into motherboard outputs (top or left). Note that not all CPUs have integrated graphics, so what is CPU?
What is motherboard? Is there any indication that it is powering on? Are there any LEDs on it lighting up to indicate a problem?
You say you rebuilt it, what if anything has changed?
Do you have a GPU or are using CPU with integrated graphics?
Where are you plugging the monitor in on the PC? If GPU, plug into that (towards bottom or right on most cases). If not, plug into motherboard outputs (top or left). Note that not all CPUs have integrated graphics, so what is CPU?
What is motherboard? Is there any indication that it is powering on? Are there any LEDs on it lighting up to indicate a problem?
You say you rebuilt it, what if anything has changed?
