What should you do if the computer turns on but shows no display?

When the computer turns on and the fans run but there is no image on the screen, the fault is usually sought along the display signal path. The first points to check are: whether the RAM modules are seated properly, the external graphics card connection, and the display output circuits on the motherboard.

Replacing parts is not recommended without performing component-level measurements. The source of the fault is determined by checking the power lines and signal paths with an oscilloscope and multimeter.