There are a number of other issues you're going to face.  Will the Alienware I/O panel fit the aftermarket case (my bet would be no)? Are you aware of the non-standard wiring Alienware uses, from the front panel to the power switch to the other case connections? Also carefully check the mounting holes - they may well not line up with an aftermarket case (though some cases have swappable standoffs, will those align with the Alienware board? Replacing the fans will likely mean wiring them directly to the power supply -- and even if the connectors fit, the Alienware case will be looking for a thermistor loop on the fan itself, so you may well find bootup errors. There is a lot to consider before trying this -- the proprietary nature of OEM systems makes it more likely you'll wind up replacing the system board with a standard one (which in turn means you'll need to budget for a full Windows license, as you cannot transfer the OEM license to a new system board).  
Hello Everyone, just wanted to let you all know I have searched all over the web, and every single other similar topic, and could not find a solution. I have the Aurora R7 and I want to swap it to the NZXT H510 case. I was wondering what parts would not fit from my old system? So far the motherboard and the PSU seem to not work, so I am planning on purchasing the following replacement parts = NEW MOBO: [URL] NEW PSU:  [URL] NEW COOLER: [URL] I am assuming the ram from the Alienware mobo will fit, along with my Intel i7-8700k CPU into the new MOBO.  Also, my GPU is a 1060 6GB. So to make sure, are these the only parts I will have to buy, will the old ram and CPU work with the new mobo?Thanks!    
Aurora R7, Case Swap, #2