adampcpower: You seem to be confusing processor usage and RAM usage. 90% in Afterburner means that it almost fully taxes the GPU (graphics card processor), it doesn't mean it needs to use more RAM... If it needed to don't worry it would use it because more is available.
Not a lot of games will require more than 1 GB. You didn't say what's your resolution, but most people play in 1920 x 1080 and that resolution rarely requires more than 1 GB. If you were playing on multiple monitors or had a monitor with higher resolution like 2560 x 1440 or 2560 x 1600 then you would see your card using more RAM.
If you reach decent FPS and your games are not sluggish, don't worry everything is fine.