My new PC uses a lot of RAM

Well, you appear to have a lot of things open- Assassin's Creed 4, as a game, will likely be using a large chunk. Close some programs you don't need open of the usage is bothering you. Maybe also make sure no malware or viruses are using any system recourses. Hope this helps.
 


i had a lot of things running but it also does it when i have pretty much nothing running 🙁
http://gyazo.com/97338250734cad1010b939edb5e80a8c
I'll try to get some anti-virus, and see if it helps
 

I have windows 8, and I think it's causing some lag in games.