Virtual memory - freezing, black screen with/and no load?

Question

Iron

Lamer, so don't hit too hard, but show me where to dig. The screen hangs, but within 5 seconds it still reacts to the mouse (moving around the screen) and to the keyboard. Then the cursor freezes, the screen throws into blackness for half a second and then it works as if nothing had happened. The load, as I understand it, does not play a role: it crashes both in the browser-max-word combination, and without load. It started recently - there was no such thing from 3d prog, anrial is standing (the service is turned off), everything is fine when watching the video, but it can crash on the Word.
The RAM is 16 gigs, and judging by the dispatcher, it does not change in any way before and after the departure, the percentage jumps to 100, there are no notifications from the video driver, and there are no card artifacts at normal times. The temperature is normal for everything: 30-40 for the mother, 40 for the mother, vidyuha 38-40.

Windows 10 Pro 1909 (when it was installed, there were a couple of lags with loading the text of the notification column, but then it disappeared - it has been working properly for several months).

Proc - Intel Core i3-2120 CPU 3.30 GHz
mother - Gigabyte GA-Z68A-D3H-B3
video - AMD Radeon HD 6850 Series
RAM - Kingston 99U5471-012.A00LF 4 GB DDR3-1333 DDR3 SDRAM - 4
bars make a swap file, but maybe that's not the point at all. As for replacing the thermal paste on the vidyuhi - does it make sense and is it possible on this one? clean the computer? The test is striving to do - there is no experience, the computer is old, I'm just learning. In addition to the fact that 3d prog services POSSIBLY load, there are no ideas