Your computer could still power on even if the RAM is missing, but you’ll notice multiple beeps immediately to let you know. This system’s self-test procedure finds any potential hardware problems and alerts you with a sequence of sounds; since the POST diagnosis detects a RAM issue, you cannot go past this stage.
Moreover, no hardware contains the fundamental functions for the computer to boot. You can notice an error message on the screen or hear beeps indicating a RAM issue if your machine has one. The power supply may also be humming, or the discs may rotate, but your computer is dead since the BIOS code cannot locate a location in RAM to boot.