Why is my screen squared with every resolution even tho my monitor is rectangle?

[Koronakis31]

Ok, before I got my pc to install a SSD, the resolution was fine, didnt need to stretch it to fit the screen, the resolution was filling the whole screen, after I got my pc to get a SSD, when I first opened my pc I saw that my screen was squared, I tried changing resolution and stuff and even brought experienced friends to help me to no avail, only way to fill the screen was to stretch it which I didnt like, it looks weird. So, does the SSD have to do anything with this? if no then how do I fix this????????