Will all these stuff fit properly in the case and all go with each other?
Also, is there any different between the sapphire 7850 regular or the 7850 OC? like the coolers and stuff? Because they are out of OC.
Yes everything will Fit. As The User Above Said it have poor cable management, But you Got a Modular Psu So Its Okay.
Actually not really - I used a modular PSU in my Antec 900 and it still caused nothing but problems - especially with air flow and system temperatures. Get a case that allows you to route your PSU cables behind the motherboard tray. With the 900 you also have to remove your motherboard if you want to install another cooler.