after trying EVERYTHING during multiple HUGE searches (russian pages, I'm also looking at you) to make the HD530 work through DP1.2 in 4k@60hz to stop flickering I found the solution.
Beside using the suggested ig-platform-id and inject Intel to true use nv_disable=1 boot flag and bam, flickering gone.
And think about that I bought a second compatible GTX (100$) to have acceleration and no flickering because in my main PCIE slot there's a GTX 1080.
The 530 flickering was given by the GTX 1080.
I could have saved the purchase of the second GTX by attempting the flag earlier.
Damn.