Unplayable FPS on a New Build

[bleepbloop]

Hey guys, I built my first PC back in October and up until recently it's been working well. Now I've been experiencing lag and choppiness for no reason. I play FFXIV:aRR on ultra and Battlefield 4 including all games before that on ultra but recently noticed these Issues after installing Metro: last light and Dark souls. It doesn't seem to matter which graphic setting I use, the slowdown makes the game unplayable. Please help I'm not really PC savvy and have no idea on my own how to resolve this.

My Specs:
Windows 7 (64) bit
Processor: i5-4670k
Graphics: AMD Radeon HD 7900 series
RAM: 8G
Mother board: AS Rock Z87 Extreme 3 LGA1150

 

[rgd1101]

brought the games from steam?
ran check disk?

 

[bleepbloop]

brought the games from steam?
ran check disk?

I did buy them from steam. Haven't ran check disk. I have a bad feeling that I have could have a defective graphics card, will that help figure it out?