The screen does not turn on when you turn on the computer?

Question

Iron

One fine day I come home, the computer turns off after starting in a couple of seconds or minutes (how lucky). I decided that the power supply, I bought it, installed it, changed the coolers, the blades were broken. I start it, either it turns off immediately, or it freezes after 3 minutes of operation, while it starts with difficulty after turning it off (you have to turn off the power for 5 seconds, sometimes it happens, and sometimes it turns on from the second press) Or the computer turns on and the screen does not respond, which I only didn’t, as a result, after cleaning and reconnecting, lubricating with thermal paste, it works, it worked for 2 hours in the evening and everything was fine, turned it on in the morning, didn’t want to start at first (it started but quickly passed out, after 15 seconds) the screen does not respond, after turning off the power, it worked, it hung and after that the screen never woke up.

Answer 1

Clean the contacts of the RAM with an eraser (only without fanaticism) and try to drive the system without hard drives. (From a flash drive) It is quite possible that the mother is doing brains.

Answer 2

Are the electrolytic capacitors swollen on the motherboard? If yes - for soldering.
PS The phrase "the screen does not respond" breaks the brain. What does he not respond to?