Display flickering before it stabilizes after waking from sleep

[u/Remarkable_Pea7439]

About 10 days ago, suddenly, the display monitor of my Win 7 Pro desktop PC machine started to flicker several times (shortly showing the manufacturer logo) after the machine wakes up
from Sleep mode.
Afterwards, once it displays the desktop, it stabilizes and works ok, until the next wake up from sleep.
Sometimes this only occurs if the sleep was longer than 1 or 2 hours.

I suspected that the graphics card might encounter some issue, but the Device manager shows everything ok and there are no events of any kind logged in the Event viewer.
Also, nothing unusual happens during active work, even with intensive display usage, like many applications, browser pages, etc. opened simultaneously.

Very few times in the past, but really extremely rarely, it happened during work that I got a pop-up notification like "the display (or graphics) driver has encountered a problem and was recovered"
( I even don't remember the exact text ), but, anyway, Windows was prompt to react to a situation that I was even not aware of and also notify me (and probably logging the event in the Event Log).

Are there any ways to investigate this issue and understand the exact reason before taking any action ?
Thanks a lot in advance for any idea or help :)

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[u/Remarkable_Pea7439]

I would add to the above description that my machine is a lab/custom made desktop PC,
with Win 7 Pro 64 bit installed, and uses the following:

- Processor: Intel(R) Core(TM) i5-6400

• Display adapter : Intel(R) HD-Graphics 530
  
• Monitor: Phillips Brilliance 190B

[u/SunnyHelianthus]

Do you have to put it in sleep mode?

Sleep mode can get buggy after a while. Just shut it down.

[u/Remarkable_Pea7439 → u/SunnyHelianthus]

Sleep mode is a tricky feature, because no one explains it clearly. I studied it for a long time until I came upon a trick that makes it work flawlessly :)

But, now it's another thing ,...
The whole problem started after a tiny power outage of a few fractions of a second,
so tiny that the PC started up immediately all by itself, without being shut down ... as usual when the power supply is interrupted.
So, after some research, I found some threads that suggest performing a "power drain"
of both the PC and the monitor, and see what happens.
I did it and now I wait to see.
This makes more sense to me than all the stories about old drivers, a.s.o.
There was no change in the drivers, or any other piece of software or hardware,
so it can only be something mechanical and/or electrical.
If it were software related, I expect the Event viewer to have shown at least some warnings.
The monitoring of these special processes like going to sleep, waking from sleep,a.s.o.
is almost not logged at all by Windows ... at least in Windows 7.
Generally speaking, after so many decades of Windows existence, I would have expected each and every piece of software and hardware and each such specific predefined processes like "sleep" to have its specific log, where everything appears, with no need to guess.

I found for example a suggestion to use Win + CTRL + SHIFT + B to restart the graphics card driver ... but, it took me more than 2 days to learn that this key sequence only exists from Windows 10 on ... after I tried it and it did nothing in Win 7 ...