The computer does not turn on. How to find the reason?

Question

Iron

Good afternoon. A common problem, but I did not find adequate advice on diagnosing the problem on the Internet.
The first time the computer froze was when I left it for two days (turned on the monitor and it was dead).
Then everything happened on one (final) day. The computer freezes 3 times in a row (in the game), then I began to look for the cause. I started to defragment the disk, at this stage it hung, and after rebooting it gave a windows error (did not have time to fix it), later it hung on loading windows mixed with the state when it did not turn on at all. Now, just this state has come, in which everything is buzzing, but the monitor is black.
I tried to play (swap and insert separately) with RAM, with a jumper and a BIOS battery. In the absence of a video card and RAM, it does not beep. Prompt, what can be proceeding from the above-described symptoms?

Answer 1

If it doesn't beep, it's either the motherboard or the power supply unit - see "swollen conduits".

Answer 2

Once it buzzes, it does not start - there is a high probability - the power supply has broken. Check the voltage, or better yet, find a working PSU and replace it.
If there are no POST-test signals, then either it does not reach the point, or there is no beeper. Is he there? Previously beeping on boot? Maybe it was turned off during disassembly?
Maybe it's the mother card. This can be achieved by the elimination method: PSU, memory, percent, visual inspection of air conditioners and chips (they can burn out). There are PCI testers with a screen, by the code on which you can get more diagnostic information, you can look for one from friends or buy it.
If the computer freezes under load, then it is probably overheating. Check the temperature in BIOS.

Answer 3

The problem may be in the motherboard and power supply
, it is also worth checking the hard drive, suddenly something happened to it