Okay, so you are using 8 GB RAM with a GTX 980. You havent mentioned the games that have issues, what settings, resoultion etc.. Also, I have no clue what your PSU is. If you can provide these details, you will get more accurate help.
If I work on assumptions GTA V at 1080p max settings or even a notch below it will stutter as it requires more RAM. It easily consumes around 10GB RAM on my setup. Check my signature. same is true for COD Advanced warfare. It consumes 12 - 13 GB RAM easily. To resolve this, turn down shadows, textures, AO till you get rid of stutters. Reducing resolution may or may not help.
If you are playing a game like Paladins or DOTA 2 at 1080p maxed out, and you still have stutters, then there can be other reasons apart from RAM. Your RAM unfortunately is a bottleneck for FHD ultra settings.
However, if you are playing at 720p or 768p maxed out and still have stutters, then either there is a corrupt driver installation or windows installation or your PSU is not providing enough power or you have air flow issues within your cabinet.
Please list down complete specs and games and resolution etc. to ge accurate help.