Enable PAE for Windows 10 pro to use more than 4 GB RAM
Windows 10 (32 bit) is limited to 4 GB even with PAE enabled. https://en.wikipedia.org/wiki/Physical_Address_Extension#Microsoft_Windows
The official Microsoft document about client OS limitations is here.
Devices have to map their memory below 4 GB for compatibility with non-PAE-aware Windows releases. Therefore, if the system has 4GB of RAM, some of it is either disabled or is remapped above 4GB by the BIOS. If the memory is remapped, X64 Windows can use this memory. X86 client versions of Windows don’t support physical memory above the 4GB mark, so they can’t access these remapped regions.
You could try some of these:
- Check BIOS settings for onboard video memory limits. BIOS might be giving away RAM for an onboard video card. Minimizing video RAM could raise 3.25 GB limit closer to 4 GB
- Check BIOS settings that might impact memory for 32-bit OS. This is really specific and depends on your motherboard manufacturer
- Install 64-bit OS on the hardware and use Hyper-V or other virtualization technology to run your legacy app in guest 32-bit OS
- Install 32-bit server version of Windows OS which supports more than 4 GB (keep in mind that all 32-bit Windows Server OSs are unsupported)
Hope this helps