There are all sorts of issues you'd need to address.  The board is proprietary enough that retrofitting it into a different chassis will be a frustrating exercise in on the fly engineering.  You'll face a host of unmarked cables that won't directly fit an aftermarket case wiring scheme, for one.  And the board likely won't line up with the openings in the back of the case and the mounting points. Pretty much forget it - you'll wind up building an effectively new system anyway, which is the better upgrade path.  
Knowing that Dell Inspiron 3250 has a small case with not a good power supply. I am thinking to buy a new bigger cabinet,along with a better power supply.So.. Will I be able to install GTX 1050 then???..pls help [NAME]  
Dell Inspiron 3250 GPU Upgrade