Black screen green dots

What was the last thing you did on your computer before this happened?
Did you change any system settings in the BIOS?
Did you add new software? or update any software or drivers?
Did you add any new hardware?
Is your system BIOS infected with a virus?
Because it appears that your PC is hanging up during the Power-On-Self-Test [POST]

Here's what happens; when the power is turned on, the computer BIOS [Basic Input/Output System] runs a POST (Power-On Self-Test). It is a diagnostic testing sequence that the computer runs to determine if the hardware [like the mouse, keyboard, hard drive, etc.] is working properly.

If the necessary hardware is detected and found to be operating properly, the computer begins to boot; If the hardware is not detected or is not operating properly, the BIOS issues an error message.

The error message may be a text on the display screen and/or a series of coded beeps, depending on the nature of the problem.

The series or pattern of beeps may vary...they may be in a number of long or short beeps or a mixture of long and short beeps, or even one long continuous beep, depending on what type of BIOS is installed.

Since POST runs before the computer's video card is activated or the integrated graphic chip on the main board, it may not be possible to progress to the display screen.

So if an error is detected during the POST it will halt the boot process because the hardware is essential for the computer's functions.

How many beeps do you hear during the initial POST?

You may have a burned out video chip/card; or corrupt drivers; or even an IRQ [Interrupt Request] conflict.