Pixelated images on samsung 27" curved

windows 10 HP Envy 750-524 i7-77003.60Ghz 16GB ram 64 bit. Bought new Samsung 27" curved monitor. images are all pixelated so i bought a XFX R7 260x Radeon graphiocs card and new 750w power supply. COmpleted installation finally got it to recognize this monitor and images are still pixelated. 1920x1080 Any ideas? I am at my wits end.