有幾台同型號的桌機，主機板上有內hdmi/dvi 接孔，也都有加裝外接顯卡，螢幕接上外接顯卡都正常運作。
但把外接顯卡拔掉，螢幕接上內建的hdmi/dvi ，就都抓不到螢幕，到bios裡也找不到可以調整了。
去查了一下該主機的手冊才發現，原因主機板上有內建的顯示接孔，不一定有用，還要看cpu有沒有支援。
怎麼查cpu有沒有支援，可以查看這篇說明
https://www.asus.com/tw/support/faq/1045576/
There are several desktop computers of the same model. The motherboards have built-in HDMI/DVI ports, and they all have external graphics cards installed. When the monitor is connected to the external graphics card, everything works fine.
However, when the external graphics card is removed and the monitor is connected to the built-in HDMI/DVI ports, the screen is not detected, and there's no option in the BIOS to adjust it.
After checking the manual for the motherboard, I found out that even though the motherboard has built-in display ports, they may not be functional depending on whether the CPU supports it.
To find out if the CPU supports it, you can refer to this guide: