Screen Pixelation

So it happened two weeks before. I was attending online classes and then suddenly my pc turns off never to start again. I took it to the place from where I bought it and they told me the motherboard is dead and nothing could be done. My PC specifications were : Gigabyte H110M-S2 Motherboard...

I just finished putting together my computer (first build) and everything is pixelated I have tried scaling, resolution, updating/uninstalling drivers, calibration, and clean text. It displays fine on other displays but my old computer (that I still use) displays the same resolution just fine...

what is the speed of write /read aplied by the games to the system? how many gb/s use by ex battlefield 1? Edits by a mod: i read that frecvency dont metter so much for gaming but i need to know if 15 gb/s as my ram is enought i know that in games is used graphic card ram but the system need...