Hey buddy! Alright. 1. I highly recommend getting a power supply separate from a case; and on that note, most of the times cases do not come with a PSUs, though if they do it's probably a shooty off brand something or the other. A good power supply is crucial in most any build as it can be the difference between a stable and possibly nicely over clocked system that is the bee's knees, and your house being a smoldering mess after a terrible electrical fire. Go with Corsair or EVGA for a power supply. Probably 500W-550 will be good for you price range the the TDP of a build like that. Yes (mostly) it is necessary to have a case. For convenience of being able to move the whole thing just yeah, get a case of course. The luxury and conveniences of the case you want is going to ultimately depend on cost. If you want great cable management, looks, functionality, an ass load of cooling solution space and what not, it all comes at a price. Not saying cases have to be expensive. Personally if you really want to shave cost honestly just e-bay/thrift/craigs list a case. If you want good cable management