Monitor Scan lines/horizontal flickering while playing games

[Anguxilion]

yesterday my dad gave to me his old monitor ViewSonic VA2016w-2 and for my surprise, it worked. this are specs of screen: http://ap.viewsonic.com/ph/products/lcd/VA2016w.php
but there is a problem and I don't know what to do, i really don't wanna buy another one or rollback to my old monitor.
when i'm playing any video game, a lot of horizontal semi-transparent bars flick arround the screen, sometimes is barely visible, other times is disgusting, they look like old crt interference when a phone was close.
the strange thing is that when i'm on desktop or watching videos on youtube (even 4k/ 60fps videos) or watching movies with splash pro ex with interpolated frames, i don't get any flick, i can see eveything okay.
here comes something weird that i found five minutes ago, if i play windowed mode, it flicks everything on the background too (desktop or whatever i have on background) but if i press click on the game (keep it pressed) the flick goes away.
I really hope you can understand my poor english and i hope you can help me to fix this, thank you for your time.


(VIDEO OF THIS) i recorded them:

- https://www.youtube.com/watch?v=pRG72TStFO4

- https://www.youtube.com/watch?v=cmpn0KtqTU4 (the thing that i've said of click the game on windowed mode)


SOLUTIONS THAT I'VE FOUND ON INTERNET THAT I TRIED (not even one worked):

-change power cable (monitor one) to another plug (now i have it pluged alone in my wall) (besides i tried a lot of cables, old and new ones)

-separate vga cable from psu (pc) cable

-pluging the monitor on the integrated gpu (it's still the same, so i doubt is my gtx)

-custom resolutions from nvidia panel and windows config (59/60hz and those kind of things)

-clean everything

-subtle pressing on corners of screen

-trying another vga cable


*i've seen on internet that change the vga cable for dvi-d solved the problem, but here is the thing, my monitor has only vga output, and my gpu nope. so i have the vga cable with a dvi-i adapter. do you think that could be better if i buy a dvi-d cable and i plug an adapter to my monitor? i don't wanna buy one just to "test" because here in argentina is very expensive*

I had no problems with my old monitor but it was very very low resolution compared to this one and it was very small idk if this is important.

 

[lumineZ]

Normaly from my experience is down to the cabel running from your gpu to the monitor.

On my old computer I had a VGA first, with "flickering waves" if one can call it that and when I added an dvi-i adapter, that only made it worse for me.
Only when I swaped to an HDMI cable it "worked"
Never got it fixed but I have figured out the problem for me atleast and the only solution was to buy a new monitor since the panel was cheap and spec`s where not good overall.

 

[Anguxilion]

Normaly from my experience is down to the cabel running from your gpu to the monitor.

On my old computer I had a VGA first, with "flickering waves" if one can call it that and when I added an dvi-i adapter, that only made it worse for me.
Only when I swaped to an HDMI cable it "worked"
Never got it fixed but I have figured out the problem for me atleast and the only solution was to buy a new monitor since the panel was cheap and spec`s where not good overall.

i fixed it five minutes ago, bought dvi-d / vga active adapter cable and works like a charm now

 

[lumineZ]

Nice