I have 32GB RAM but only 15.9GB are usable.
There may be 2 problems
| Problem | Solution |
|---|---|
| You have Windows Vista - 7 / Home Edition | Upgrade your OS to Windows 10 for free |
| Problem with computer BIOS | Flash your motherboard BIOS to latest from manufacturer website |
| OS | Architecture | Memory Limit |
|---|---|---|
| Windows * | 32bit | 4GB minus HW address space |
| Windows 7 Home Basic | 64bit | 8GB SW Limited |
| Windows 7 Home Premium | 64bit | 16GB SW Limited |
| Windows 7 Pro | 64bit | 192GB |
| Windows 8 | 64bit | 128GB |
| Windows 8 Pro | 64bit | 512GB |
| Windows 10 Home | 64bit | 128GB |
| Windows 10 Pro | 64bit | 2TB |
| Linux * | 32bit | 4GB - 1/3GB and 2/2GB |
| Linux * | 64bit | 64TB |
Under 32bit Windows single process cannot use more than 2GB RAM.
Under 32bit Linux there are two configurations 1GB (default) and 2GB (not standard).