Why Doesn’t Windows Use All Your RAM? (32 GB Installed, 31.2 GB Usable)

You’ve installed 32 GB of RAM on your PC, but Windows only shows 31.2 GB as “usable”? Even worse, some users find that with 16 GB installed, they can barely access 12 or 13 GB. So, where did the missing gigabytes go? Is it a bug? Is your RAM defective? Rest assured, in the vast majority of cases, everything is functioning normally. Here’s a simple explanation of why that is.

Installed RAM vs Usable RAM: What’s the Difference?

When you open Windows system information or the task manager, you often see two values:

• Installed memory (e.g., 32 GB)
• Usable memory (e.g., 31.2 GB)

The first represents the amount of physical memory your motherboard detects. The second indicates how much memory Windows allows you to use for your applications, games, or daily tasks.

And no, it’s not a Microsoft conspiracy to steal your RAM 😅

Why Is Not All RAM Usable?

1. A Portion Is Reserved for Hardware (Especially for Integrated Graphics)

If your processor has an integrated graphics chip (like Intel UHD or AMD Radeon Graphics), part of the RAM is automatically allocated to that graphics chip.

For instance, it’s common for 512 MB, 1 GB, or even 2 GB to be reserved just for the integrated GPU—especially if you don’t have a dedicated graphics card. This is likely the main reason you don’t see the full amount of RAM in Windows.

2. BIOS/UEFI Settings

Some motherboards allow you to manually set the amount of memory allocated to the integrated GPU. So, if your BIOS is configured to reserve 2 GB for the iGPU, that amount will be deducted from the “usable GB” in Windows.

💡 Note: On systems with a dedicated graphics card (AMD, NVIDIA, or Intel), it may sometimes be possible to reduce or even disable this allocation in the BIOS.

3. 32-bit Windows (Yes, still in 2025…)

Though rare today, if you are still using a 32-bit version of Windows, be aware that it can only handle up to 4 GB of RAM, regardless of how much you have installed. So if you have 8 GB, 16 GB, or 32 GB… Windows will only use 4, and often much less.

4. Hardware Incompatibility or Bugs

A poorly seated RAM stick, an outdated BIOS, or a limited motherboard can sometimes cause partial detection of RAM. This is quite rare, but it can happen, especially on older or unusual setups.

5. Memory Reserved for the System

Even without an iGPU and with a modern motherboard, Windows may reserve a small part of the RAM for some low-level components (like the BIOS, drivers, or the kernel).

This explains why you might see 31.2 GB usable with 32 GB installed, as is the case with the PC I’m currently using.

How to Check What’s Going On?

1. Use “System Information” (msinfo32)
   • Press Windows + R, type msinfo32, then press Enter.
   • Look at the lines for Installed Physical Memory (RAM) and Total Physical Memory.
2. Check the Task Manager
   • CTRL + Shift + Esc > Performance tab > Memory
   • Here, you’ll see installed, used, cached memory, and reserved hardware memory.
3. (Optional) Check Settings in BIOS
   • Enter BIOS at startup (Delete, F2, etc.).
   • Look for an option related to shared video memory or the integrated GPU.

Should You Be Worried?

No, unless:

• The difference between installed RAM and usable RAM is significant (e.g., 8 GB installed, 3 GB usable).
• You are on a 32-bit version of Windows (if so, switch to 64-bit quickly).
• Your system becomes unstable without apparent reason.

In 99% of cases, seeing 31.2 GB usable out of 32 GB installed is perfectly normal. It simply means a small portion is reserved for the internal functioning of the system.

In Conclusion

Windows isn’t hiding RAM from you. If part of your memory isn’t “usable,” it’s reserved for hardware or for ensuring system stability. In most cases, there is absolutely nothing to correct.

But now that you know where the difference comes from, you can stop searching for your missing gigabytes in the corners of your case. 😉