Flickering of background and interface of heavy apps

Guys, I'm going crazy with screen flickering in Photoshop and Davinci Resolve. It is very difficult to work...

In both cases flickering doesn't go outside of the program, its just withing the app itself. However, Davinci Resolve flickers a lot at random times in all windows (edit, colorcorrection, while rendering (but this flicker doesn't affect the final videos, they are just fine). And Photoshop dims the background and panels and tables of the app every time I press touchpad/mouse/tablet pen - means when some drawing is in process and as soon as I release the button - app brightens itself back. 

I could not find way around Davinci Resolve but after digging into forums I found out that if I disable and enable Intel Graphics driver when PH is running - flickering will stop for an hour or so but then will start again and I will have to repeat whole process and it is not fun as I edit photos and videos for hours on a daily basis. 

I tried to contact Dell support but they just claim that their drivers and everything is top-notch and there is not a slightest possibility of anything running incorrectly (yeh, I just imagining this flickering in 2 apps, right). 

I checked all the settings, point both apps to work with NVIDIA and not Intel, point NVIDIA as the graphic card for these apps in NVIDIA CP and turned off all smart and auto options in Intel CP. Any ideas?