You will need to furnish a few more details if you want anything approaching a constructive answer. For instance....
Budget.
Location / Likely retail/etail purchase outlets.
What level of gaming you actually want to achieve.
The monitor/screen resolution will you likely be gaming at.
Whether the system will be used as an all-rounder (home theatre/multimedia, storage)
Will you be utilizing some componentry from your present build ?
What are your connectivity requirements ?
Do you need to factor an operating system and/or software into the build budget ?
There are already numerous threads on Techspot regarding ground-up system builds. I would suggest you peruse the latest threads and have a relatively clear idea of what end product you want to end up with.
If you cut-and-paste the bullet points from this
thread starter- and your answers, along with your thoughts on what you want the build to accomplish then you will likely get replys of a more constructive nature that are better tuned to your requirements.