Microsoft has quietly changed the minimal hardware requirements for a Windows 10 Mobile smartphone. They must now have at least 1GB of RAM and 8GB of internal storage, up from the previous requirements of 512MB of RAM and 4GB of storage.
Microsoft previously set the requirements for Windows 10 Mobile hardware products in March 2015, before the OS officially launched several months later. However, the newly updated requirements (via NPU) indicate that the company has decided the new OS needs some beefier hardware to run well.
The updated requirements are also in line with Microsoft's recent changes for older Windows Phones that can be upgraded to Windows 10 Mobile. The company recently announced that none of those phones with just 512MB of RAM will be eligible for the Windows 10 Mobile update