Making a Gaming Rig. Some parts still missing.

[Kritzk]

Here are the initial parts of the rig but I have a little know how about the Mobo, PSU, Casing, and Optical Drive. Can you give me your best suggestions that would complete the rig? I need the highest value to performance ratio for the parts.

FX-6300 3.5GHz
Sapphire R9 270X
G.Skill Ripjaws 2x4GB
WD 1TB Black

Lacking:
Mother Board
PSU Bronze/True Rated
Tower Casing
Optical Drive

 

[Aspire77360]

WHta is your budget?

 

[Kritzk]

$900

 

[Aspire77360]

Is that budget for the whole system or just additional extras? And do you need an OS?