Should You Use ReadyBoost in Windows 10 and 11 in 2026?

ReadyBoost is still built into Windows 10 and 11, but whether it’s worth using in 2026 depends almost entirely on what’s inside your PC. If you have a mechanical hard drive and 4 GB of RAM or less, it might genuinely help. If you have an SSD or more than 8 GB of RAM, skip it. Windows will likely tell you the same thing.

What is ReadyBoost?

ReadyBoost is a Windows feature that uses a USB flash drive or SD card as a read cache for your system. It does not add RAM, that’s the most persistent myth about it. What it does is store frequently accessed data on the flash device so Windows can retrieve it faster than it could from a slow mechanical hard drive.

On a system with an SSD, this is pointless. SSDs already read small random files far faster than any USB drive can. ReadyBoost only makes sense when the bottleneck is a slow spinning hard drive and there isn’t enough RAM to cache everything in memory.

ReadyBoost depends on the SysMain service (previously called SuperFetch) to function. If that service is disabled, the ReadyBoost tab will be missing or greyed out.

Is ReadyBoost Worth Using?

Here’s an honest answer based on current hardware realities:

Your setup	ReadyBoost verdict
HDD + 4 GB RAM or less	Worth trying, you may see a modest improvement
HDD + 8 GB RAM or more	Unlikely to help, RAM is already sufficient
SSD (any amount of RAM)	No benefit, Windows may refuse to enable it
NVMe SSD	No benefit whatsoever

If you’re hoping ReadyBoost will rescue a sluggish PC, the two upgrades that actually move the needle are adding physical RAM and replacing a mechanical HDD with an SSD. Even a cheap SATA SSD will outperform any ReadyBoost setup by a wide margin.

Requirements

Before trying to enable ReadyBoost, confirm your setup meets these requirements:

• OS: Windows Vista or later, including Windows 10 and Windows 11

• System drive: A mechanical HDD (SSD systems will see no benefit and may be blocked)

• RAM: 4 GB or less for best results

• Flash device: At least 256 MB free (practically, use 4 GB or more); USB 2.0 or higher, or a fast SD card

• File system: NTFS preferred; exFAT also works and supports caches larger than 4 GB

• SysMain service: Must be running (see Fix #1 below if the ReadyBoost tab is missing)

Windows automatically tests whether your flash device is fast enough when you open the ReadyBoost tab. If it fails the test, you’ll see “This device cannot be used for ReadyBoost”, which means the drive is either too slow or your system drive is already fast enough that ReadyBoost offers nothing.

How to Enable ReadyBoost in Windows 10 and 11

Fix #1: Check that the SysMain service is running

If the ReadyBoost tab is missing from your drive’s Properties dialog, SysMain is almost certainly disabled. Fix that first.

1. Press Windows + R, type services.msc, and press Enter.

2. Scroll down and double-click SysMain.

3. Set Startup type to Automatic.

4. If Service status shows Stopped, click Start.

5. Click Apply, then OK.

Once SysMain is running, plug in your USB drive or SD card and continue to the next step.

Fix #2: Enable ReadyBoost from File Explorer

1. Press Windows + E to open File Explorer.

2. In the left pane, click This PC.

3. Right-click your USB flash drive or SD card and select Properties.

4. Click the ReadyBoost tab.

5. Windows will test the device. If it passes, you’ll see three options:

• Do not use this device, disables ReadyBoost for this drive

• Dedicate this device to ReadyBoost, uses the entire drive as a cache (recommended if you’re committing the drive to this purpose)

• Use this device, lets you set how much space to allocate with a slider

6. Select Dedicate this device to ReadyBoost or use the slider to set an amount, typically 1–8 GB depending on your drive’s capacity.

7. Click Apply, then OK.

Windows will create a ReadyBoost.sfcache file on the drive. Leave the drive plugged in, as removing it while ReadyBoost is active discards the cache (though it won’t damage anything).

Fix #3: Disable ReadyBoost

If you want to reclaim the drive or stop using ReadyBoost:

1. Open File Explorer and go to This PC.

2. Right-click the drive and select Properties.

3. Click the ReadyBoost tab.

4. Select Do not use this device.

5. Click Apply, then OK.

Windows will delete the cache file and the full drive space will be available again.

Why You’re Seeing “This device cannot be used for ReadyBoost”

This message appears for one of three reasons:

• Your system drive is an SSD. Windows detects that the SSD is already faster than the flash device and disables ReadyBoost automatically. This is the most common reason on modern PCs.

• The flash device is too slow. Windows runs a speed test when you open the ReadyBoost tab. If the drive fails the minimum random read/write thresholds, it’s rejected. Try a faster USB drive.

• Not enough free space. The drive needs at least ~230 MB free, though practically you want 4 GB or more to see any benefit.

Better Alternatives to ReadyBoost

If ReadyBoost isn’t an option, or you want a real performance improvement, these alternatives deliver more noticeable results:

• Add more RAM. This is the single most effective upgrade for a RAM-constrained system. Aim for at least 8 GB for comfortable everyday use in Windows 10 or 11.

• Replace your HDD with an SSD. Even a budget SATA SSD will make Windows feel dramatically faster. Boot times, app launches, and file operations all improve immediately.

• Trim startup programs. Press Ctrl + Shift + Esc, go to the Startup tab in Task Manager, and disable anything you don’t need loading at boot.

• Run Storage Sense or Disk Cleanup. Freeing up disk space on a nearly full HDD can improve performance on its own.

• Keep Windows and drivers updated. Performance and stability patches ship regularly through Windows Update.

The Bottom Line

ReadyBoost is worth enabling if you’re running Windows on a mechanical hard drive with 4 GB of RAM or less and you have a spare USB drive sitting around. You might see a modest improvement in responsiveness, and it costs nothing to try. If your PC has an SSD or 8 GB or more of RAM, don’t bother. Windows will likely block it anyway, and your time is better spent on a RAM upgrade or SSD swap, both of which will make a far more noticeable difference.