desktop broke, should a pc display show something if you turn it on with no cpu?

If you know about repairing a desktop. A desktop stopped with a big noise. It sounded like in the videos you can watch. You cannot see on the cpu that it is damaged. The psu broke. Checked it by wiring green and black wire. I got a new psu. Put it into the desktop and the mentioned cpu. When turning on the computer the cpu fan and psu fan starts. Nothing shows on the display. I cannot turn off the computer pressing the on-button. Same if I remove the cpu. Nothing shows on the display. Assuming the cpu is broke, if the mainboard is not damaged should the display show something if the mainboard is turned on with no cpu? The gnulinux system hdd did not break and I put it into another computer.