Why Reserved Storage Triggers a Low-Memory Warning at First Boot on Windows 11

When you first boot a new Windows 11 device or after a clean installation, you may see a low-memory warning shortly after the desktop appears. This warning indicates that system memory is running low, even though you have not opened any applications. The root cause is the Reserved Storage feature, which Windows 11 uses to reserve disk space for updates, temporary files, and system caches. During the first boot, the operating system initializes this reserved space, which can temporarily spike memory usage and trigger the warning. This article explains why Reserved Storage causes this behavior and how you can verify and manage it.

Why Reserved Storage Causes a Low-Memory Warning on First Boot

Reserved Storage is a feature introduced in Windows 10 version 1903 and fully integrated into Windows 11. It sets aside a portion of disk space, typically between 7 GB and 8 GB, to ensure that updates, temporary files, and system caches always have room to operate. On a new device or after a clean installation, Windows 11 must populate this reserved space during the first boot sequence. This process involves downloading update metadata, creating temporary files for system components, and initializing caches for features like Windows Search and Windows Defender.

The low-memory warning appears because the system memory RAM is also used during this initialization. While Reserved Storage is a disk-based feature, the act of preparing it consumes memory. The operating system loads update files into memory, decompresses them, and writes them to the reserved disk area. On devices with limited RAM — 4 GB or 8 GB — this temporary spike can push memory usage close to 90 percent, triggering the warning. The warning is usually transient and disappears once the initialization completes, which can take between 5 and 15 minutes.

Another factor is that Windows 11 enables Memory Integrity, also known as Hypervisor-protected Code Integrity, by default on new devices. This feature checks drivers and system code in a virtualized environment, which increases memory usage during first boot. Combined with Reserved Storage initialization, the memory load can cross the threshold for a low-memory warning.

What Exactly Is Reserved Storage

Reserved Storage is a hidden partition on your system drive. It is not visible in File Explorer. To see its size, go to Settings > System > Storage > Show more categories > System & reserved. The reserved space is listed under Reserved Storage. Windows 11 uses this space for:

• Feature updates — space for downloading and preparing new Windows versions
• Quality updates — space for monthly security patches
• Temporary files — space for system caches and logs

The size of Reserved Storage can grow over time, but it is capped at around 8 GB on most systems.

Steps to Check Reserved Storage Size and Memory Usage During First Boot

If you see a low-memory warning at first boot, follow these steps to confirm that Reserved Storage is the cause and to monitor the situation.

1. Open Task Manager to check memory usage
   Press Ctrl + Shift + Esc to open Task Manager. Click the Performance tab and select Memory. Look at the In Use value. If it shows 80 percent or higher usage with no applications open, the system is likely initializing Reserved Storage.
2. Wait 10 to 15 minutes and recheck memory usage
   Leave the device idle. Do not open any applications. After 10 to 15 minutes, check Task Manager again. If memory usage drops below 60 percent, the initialization has finished and the warning will not reappear.
3. Verify Reserved Storage size
   Open Settings > System > Storage > Show more categories > System & reserved. Look for the Reserved Storage entry. On a fresh installation, it should be between 7 GB and 8 GB. If it is significantly smaller, the initialization may still be in progress.
4. Check for pending updates
   Open Settings > Windows Update and click Check for updates. If updates are downloading, they are using Reserved Storage. Let the updates complete and restart the device. After restart, the low-memory warning should stop.
5. Disable Memory Integrity temporarily if needed
   Open Settings > Privacy & security > Windows Security > Device security > Core isolation details. Turn off Memory integrity. Restart the device. This reduces memory usage during first boot. Re-enable it after the warning disappears.

These steps help you confirm that Reserved Storage is the underlying cause. If the warning persists beyond 30 minutes, there may be a different issue, such as a driver conflict or a corrupted system file.

If the Low-Memory Warning Persists After First Boot

In most cases, the low-memory warning disappears after the first boot initialization completes. However, some users report that the warning returns after subsequent restarts or appears every time the device starts. This indicates a different problem.

Low-Memory Warning Appears on Every Boot on Windows 11

If the warning appears each time you start the device, Reserved Storage is not the cause. The issue is likely that the system is configured with insufficient RAM for the applications you run. Windows 11 requires a minimum of 4 GB of RAM, but 8 GB is recommended for typical business use. If you have 4 GB, close background applications and disable startup programs. Open Task Manager > Startup and disable unnecessary items. Also check for memory leaks in drivers or third-party software by updating all drivers from the manufacturer’s website.

System Reserved Storage Size Is Over 10 GB on Windows 11

Reserved Storage should not exceed 8 GB. If it is larger, the system may have accumulated temporary files or update remnants. Run Disk Cleanup: open File Explorer, right-click the system drive C:, select Properties > Disk Cleanup. Click Clean up system files. Check the boxes for Windows Update Cleanup and Delivery Optimization Files. Click OK to delete them. This can reduce Reserved Storage to its normal size.

Low-Memory Warning After a Feature Update on Windows 11

After a major feature update, Windows 11 reinitializes Reserved Storage. This can trigger a temporary low-memory warning similar to the first boot scenario. Wait 15 minutes after the update completes. If the warning persists, run the System File Checker: open Command Prompt as administrator and type sfc /scannow. This repairs corrupted system files that may be causing the memory issue.

Item	First Boot Normal Behavior	Persistent Low-Memory Warning
Memory usage	Spikes to 80-90% then drops below 60% within 15 minutes	Stays above 80% even after 30 minutes
Reserved Storage size	7-8 GB	Over 10 GB or below 2 GB
Root cause	Initialization of Reserved Storage and update metadata	Insufficient RAM, driver memory leak, or corrupted system files
Recommended action	Wait 15 minutes and restart	Disable startup programs, run Disk Cleanup, or run SFC scan

If you have 4 GB of RAM, consider upgrading to 8 GB or more. This is the most reliable way to prevent low-memory warnings during Reserved Storage initialization and daily use. You can also disable Reserved Storage using the Disk Cleanup tool, but this is not recommended because it can cause update failures. Instead, let the initialization complete and the warning will stop.