32GB RAM installed but only 16GB useable (Windows 10)

Understanding and Resolving Total RAM Recognition Issues in Windows 10: A Comprehensive Guide

Introduction

Many users encounter a perplexing issue where their computer’s BIOS or hardware detects a certain amount of installed RAM, yet Windows 10 only reports a portion of that memory as usable. For example, a common scenario involves installing 32GB of RAM but Windows showing only 16GB as usable. This discrepancy can impact system performance, especially for demanding tasks such as gaming, rendering, or heavy multitasking. In this article, we will explore potential causes, troubleshooting steps, and solutions to help you accurately utilize your installed RAM.

Scenario Overview

Consider a system with the following specifications:

Motherboard: MSI B450 Tomahawk ATX AM4
CPU: AMD Ryzen 5 2600 Six-Core Processor
RAM: Corsair Vengeance LPX 16GB (2 x 8GB) DDR4-2666 CL16
Graphics Card: AMD Radeon RX 5700 XT

The user has installed an additional 2 x 8GB RAM sticks, aiming to upgrade total RAM to 32GB. However, Windows 10 System Properties indicates “16.0GB usable” despite the total physical memory being recognized by the system.

Common Troubleshooting Steps Attempted

Updating Windows 10 to the latest version
Swapping RAM sticks and rebooting to rule out faulty modules or slots
Unchecking the “Maximum memory” box in MSconfig to ensure no manual limits are set

Possible Causes and Solutions

Memory Remapping and BIOS Settings
Enable Memory Remapping:
Access BIOS/UEFI settings during startup (usually by pressing Delete or F2) and verify that Memory Remapping (sometimes called “Memory Hole” or similar) is enabled. This feature allows the system to address all installed RAM, especially in systems with large memory amounts.
Faulty or Incompatible RAM Modules or Slots
Compatibility Check:
While the new RAM modules are identical in specifications, it’s wise to test each stick individually to confirm they are functioning correctly and are recognized by the system.
Slot Testing:
Use one RAM stick at a time in different slots to identify potential faulty slots or modules.
Physical Inspection and Reseat
Proper Installation:
Ensure that RAM modules are securely installed in the correct slots according to the motherboard manual, which often recommends populating specific slots