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.

Windows shows less RAM than installed

The reduction in available system memory depends on the configuration of the following: 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 that has 4 GB of memory installed (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 for the segment of system memory that was 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 BIOS configuration utility on the computer. View your computer product documentation for instructions that explain how to enable this feature. 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 have to read the descriptions of the various BIOS configuration settings that are available to determine whether any of the settings enable the memory remapping feature. There are several additional situations that could cause the usable RAM to be 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. Windows Server may support up to 24Tb.

How to increase the usable RAM on a PC

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 seeCheck BIOS settingsEnable the memory remapping featureChange the AGP video aperture size in the BIOS settingsCheck the RAM for physical defectsCheck whether you have bad memory modulesMake sure that the memory arrangement is correctCheck whether memory standoff cards are used.

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