Use a Flash Drive as RAM in Windows: Steps

ReadyBoost is a Windows feature that lets you use a flash drive or SD card as extra memory to speed up your PC, especially when RAM is tight. This guide walks you through enabling ReadyBoost, which is the only built-in, safe way to use a flash drive as RAM in Windows. Before you start, make sure you have a USB 3.0 flash drive (or SD card) with at least 4GB of free space, and that your PC has a USB port that supports USB 3.0 for best performance.

What You’ll Need

A USB flash drive or SD card (USB 3.0 recommended) with at least 4GB of free space.
A Windows PC (Windows 7, 8, 10, or 11) with a USB port (preferably USB 3.0).
Administrator access to your computer.

Step-by-Step

Insert the flash drive into a USB port on your computer. Wait a few seconds for Windows to recognize it.
Open File Explorer (Windows key + E). In the left sidebar, click on “This PC” (or “My Computer” in older versions).
Right-click on the flash drive’s icon (under “Devices and drives”) and select “Properties” from the context menu.
In the Properties window, click on the “ReadyBoost” tab.
If the tab says “This device cannot be used for ReadyBoost,” your drive may be too slow or not compatible. Try a different drive or check the troubleshooting section below.
Select the option “Use this device.” Then, use the slider to choose how much space to reserve for ReadyBoost. Windows suggests a recommended amount (typically 1-3 times your system RAM, but not more than the free space on the drive). For example, if you have 8GB of RAM, you might allocate 8GB or 16GB.
Click “Apply” and then “OK.” Windows will start using the flash drive as cache memory. You may notice a brief pause while it configures.
Leave the flash drive plugged in. If you remove it, Windows will simply stop using it, and your PC will revert to normal performance.

Common Mistakes

Using a USB 2.0 drive: ReadyBoost needs a fast drive (at least 2.5 MB/s read and 1.75 MB/s write). USB 2.0 drives are often too slow and will be rejected by Windows.
Allocating too much space: ReadyBoost works best when the cache size is between 1x and 3x your system RAM. Allocating more than that doesn’t help and wastes space.
Removing the drive without ejecting: While ReadyBoost is designed to handle sudden removal, it’s safer to use “Safely Remove Hardware” to avoid any data corruption.
Using a drive that already has files: ReadyBoost can use free space on a drive that has files, but it’s cleaner to use a dedicated drive. If the drive is nearly full, you won’t have enough space.
Expecting a huge performance boost: ReadyBoost helps with random reads/writes, not heavy multitasking. It won’t turn a low-RAM PC into a gaming rig.

Tips

Use a USB 3.0 drive and plug it into a USB 3.0 port (the blue ones) for the best speed.
If you have multiple flash drives, you can enable ReadyBoost on more than one, but the combined cache should not exceed 32GB (or 256GB in Windows 10/11 with large drives).
For laptops, an SD card in the built-in slot is a neat way to add ReadyBoost without a dangling USB stick.
Check your system RAM: ReadyBoost is most effective when you have 1GB to 4GB of RAM. If you have 8GB or more, the benefit is minimal.
Keep the flash drive plugged in permanently if you rely on ReadyBoost. Every time you remove it, the cache is lost.

Troubleshooting

“This device cannot be used for ReadyBoost” error: This usually means the drive is too slow. Try a different drive, or format it to NTFS (right-click > Format) and try again. Also, ensure the drive has at least 4GB free.
ReadyBoost tab is missing: Your drive may be connected via a USB hub that doesn’t support ReadyBoost. Plug it directly into the motherboard’s USB port. Also, check if your PC has a policy that disables ReadyBoost (search for “ReadyBoost” in Group Policy Editor).
No performance improvement: If you don’t see a difference, your RAM might be sufficient, or your drive is too slow. Run a benchmark tool like CrystalDiskMark to see if your drive meets the speed requirements.
Windows says “This device is not suitable for ReadyBoost” after it worked before: The drive might be failing or fragmented. Reformat it and try again. If it persists, replace the drive.
Cannot allocate more than 4GB: If your drive is formatted as FAT32, the max file size is 4GB. Reformat to NTFS or exFAT to use larger cache sizes.
ReadyBoost cache is automatically cleared: This is normal if you remove the drive. If it happens while plugged in, check for power management settings that might be turning off the USB port (Device Manager > USB Root Hub > Power Management > uncheck “Allow the computer to turn off this device”).

Frequently Asked Questions

Does ReadyBoost actually work like adding RAM?

No. ReadyBoost is a disk cache, not RAM. It speeds up access to frequently used files by storing them on a fast flash drive, but it doesn’t increase your system’s total memory capacity. It’s best for systems with small RAM (2GB-4GB) and slow hard drives.

Can I use any USB flash drive for ReadyBoost?

No. Your drive must meet minimum speed requirements (2.5 MB/s read, 1.75 MB/s write). Most USB 3.0 drives meet this, but some cheap USB 2.0 drives don’t. Windows will tell you if the drive is not suitable.

How much space should I allocate for ReadyBoost?

Windows recommends 1-3 times your system RAM. For example, if you have 4GB of RAM, allocate 4-12GB. Allocating more than 3x RAM provides no additional benefit.

Will ReadyBoost damage my flash drive?

It can reduce the lifespan of the drive because it performs many read/write operations. However, modern flash drives have wear leveling and can last years. Use a drive you don’t mind replacing.

Can I use an SSD as a ReadyBoost drive?

Technically yes, but it’s pointless. If you have an SSD, it’s already faster than a flash drive, so ReadyBoost won’t help.

Does ReadyBoost work on Windows 11?

Yes, ReadyBoost is still available in Windows 11, though Microsoft has de-emphasized it. It works the same way as in Windows 10.

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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