You may have noticed that your Windows OS shows usable memory as less than installed memory (RAM). For instance, your Windows OS 32-bit, may report that there is only 3.5 GB of usable system memory when 4 GB of memory has been installed. Or, a Windows OS 64-bit computer may show only 7.1 GB of usable system memory when 8 GB of memory may be installed.
Installed RAM vs Usable RAM
The indicative Usable Memory is a calculated amount of the total physical memory minus “hardware reserved” memory.
To view the installed memory and the usable memory in Windows 7:
- Click Start, right-click Computer, and then click Properties.
- View the Installed memory (RAM) value under System. For example, if it displays 4.00 GB (3.5 GB usable), this means that you have 3.5 GB of usable memory out of 4 GB of installed memory.
Why is usable RAM less than installed in Windows 11
The reduction in available system memory depends on the configuration of the following:
- The devices installed in the computer and the memory reserved by those devices. This is called Hardware Reserved Memory.
- The ability of the motherboard to handle memory
- The System BIOS/UEFI version and settings. Certain BIOS settings (like memory remapping) can affect how much RAM is available to the OS.
- Mismatched RAM Modules. If one stick of RAM isn’t seated properly or is incompatible, Windows may detect it but not use it fully.
- The version of Windows OS that is installed
- Other system settings. In MSCONFIG, under Boot → Advanced Options, there’s a setting for maximum memory. If this is checked and set incorrectly, it can artificially limit usable RAM.
Read: Find out Computer RAM, Graphics Card/Video memory of your Windows PC.
If, say, a computer has 4 GB of RAM installed, the system memory that is reported in the System Information dialog box in Windows is less. For example, the System Information dialog box may report 3,120 MB of system memory on a computer with 4 GB of installed memory (4,096 MB). If a computer has many installed devices, the available memory may be reduced to 3 GB or less.
However, the maximum memory available in 32-bit versions of, say, Windows 7, is typically 3.12 GB. This behavior is the expected result of certain hardware and software factors. For Windows to use all 4 GB of memory on a computer that has 4 GB of memory installed, the computer must meet the following requirements:
- The chipset must support at least 8 GB of address space.
- The CPU must support the x64 instruction set. The AMD64 CPU and the Intel EM64T CPU support this instruction set.
The BIOS must support the memory remapping feature. The memory remapping feature allows the segment of system memory previously overwritten by the Peripheral Component Interconnect (PCI) configuration space to be remapped above the 4 GB address line. This feature must be enabled in the computer’s BIOS configuration utility. Refer to your computer product documentation for instructions on how to enable this feature.
Windows shows less RAM than installed
Many consumer-oriented computers may not support the memory remapping feature. No standard terminology is used in documentation or in BIOS configuration utilities for this feature. Therefore, you may need to read the descriptions of the available BIOS configuration settings to determine whether any enable the memory remapping feature.
There are several additional situations that could result in usable RAM being less than expected.
RAM supported by your Windows OS
How much RAM does each edition of Windows support? Windows 11/10 comes in different flavors—Home, Education, Pro, and Enterprise, and so the RAM supported varies. A 32-bit version of Windows can only address up to 4 GB of RAM, regardless of how much is installed.
| Version | Limit on 32-bit or x86 | Limit on 64-bit or x64 |
|---|---|---|
| Windows 11/10 Enterprise | 4 GB | 6 TB |
| Windows 11/10 Education | 4 GB | 2 TB |
| Windows 11/10 Pro for Workstations | 4 GB | 6 TB |
| Windows 11/10 Pro | 4 GB | 2 TB |
| Windows 11/10 Home | 4 GB | 128 GB |
Windows Server may support up to 24Tb.
How to increase the usable RAM on a Windows computer
You may try the following suggestions to increase the usable RAM on your computer:
- Open the Boot Advanced Options in MSCONFIG and uncheck the Maximum Memory checkbox.
- Update the system BIOS and see
- Check BIOS settings
- Enable the memory remapping feature
- Change the AGP video aperture size in the BIOS settings
- Check the RAM for physical defects
- Check whether you have bad memory modules
- Make sure that the memory arrangement is correct
- Check whether memory standoff cards are used.
Also read:
- Physical memory allocation and memory status in Windows
- Physical Memory Limits for Windows
- Maximum memory (RAM) limit for 64-bit Windows.
