PC won't start



Basically heres what happens:

1. Press the power button to turn the PC on
2. Everything starts to power on inside the PC(LEDs, fans, etc.)
3. One second passes
4. PC abruptly shutsdown

This started happing today. Yesterday and all days preceeding to today it was working fine. Sometimes I manage to get inside my OS interface, but eventually(~4-5 minutes) it shutsdown anyways.

I just cleaned my PC from dust, especially CPU HSF which had 3mm layer of dust right below the fan itself. No good did it do though.

Also my computer monitor started to randomly go "black screen" on me a few days earlier that the main issue, but it tends to occur much less. It doesn't get powered off, but fills up with black color(as if you would use the Paint's fill tool with black color to fill the screen).

What's going on?
Dust would have been the first thing I would have looked at, have you looked at the CPU temperatures in the BIOS? Also look at the heatsink and fan of the graphics card that also is probably clogged up with dust
The second thing that I would try is another power supply.