Why doesn't my computer turn on intermittently?

Question

Iron

Hello!
Please tell me why my computer does not turn on periodically, while the HDD indicator is constantly on red.
A photo of the loading screen that comes to is in the attachment. At the same time, when I press del or f7, nothing works, the computer just restarts itself.
Sometimes it helps, just get and put back the RAM, this time it does not react at all.
What should be done and where to dig?

Answer 1

Start by measuring the CMOS battery, if the nominal voltage is less than 3V, replace it.
Well, to test such floating faults, you usually need prof. equipment - testers, post cards, etc., or obviously working components. It is tested by the method of poking components, and a working run.

Answer 2

To begin with, all the same, upload a picture where it comes to you.