What Is an SFCACHE File Used For?

SFCACHE files are ReadyBoost virtual RAM files

USB flash drive and multiple USB port malfunctions

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A file with the SFCACHE file extension is a ReadyBoost Cache file that's created on a compatible USB device, like a flash drive or SD card, that Windows is using for extra memory. It's normally called ReadyBoost.sfcache.

ReadyBoost is a feature in Windows 10, Windows 8, Windows 7, and Windows Vista where the operating system improves system performance by dedicating unused hardware space as virtual RAM — the SFCACHE file holds the data stored in this virtual RAM space.

While physical RAM is the fastest way to access data, using flash memory is even faster than accessing the same data on a hard drive, which is the whole idea behind ReadyBoost.

How to Open an SFCACHE File

SFCACHE files are part of the ReadyBoost feature and should not be opened, deleted, or moved. If you'd like to remove the SFCACHE file, disable ReadyBoost on the drive.

Disabling ReadyBoost and removing the SFCACHE file is as simple as right-clicking (or tapping-and-holding) the device and choosing Properties. In the ReadyBoost tab, just select the option called Do not use this device. If you're looking to enable ReadyBoost, you can do that, too, from the same place — you have the option to use the entire device for virtual RAM or just a section of it.

Not all devices are fast enough to support ReadyBoost. You'll know this if when attempting to set it up, you see a This device cannot be used for ReadyBoost message.

If you want to use SFCACHE on your device, make sure it has:

  • A total storage capacity of at least 256 MB
  • At least 64 KB of free space available
  • An access time of 1 ms or less
  • At least a 2.5 MB/s throughput for 4 KB read access
  • At least a 1.75 MB/s throughput for 1 MB write access

It's a good bet that the only use for SFCACHE files is with ReadyBoost, meaning there's never a need to open the file. However, if your SFCACHE file doesn't seem to have anything to do with ReadyBoost, Try using a free text editor to open the file as a text file. You may find some text within the contents of the file that can help you identify what program was used to build your specific SFCACHE file.


SFCACHE files are similar to CACHE files in that they're both used to store temporary data for the purpose of repeated access and improved performance.

However, CACHE files are more of a general name and file extension for temporary files used in lots of different software programs, which is why it's safe to clear them out.

SFCACHE files are reserved for a different purpose, acting more like physical RAM and used solely with the ReadyBoost feature in Windows operating systems.

How to Convert an SFCACHE File

Most files can be converted to other formats using a free file converter, but that's not the case for SFCACHE files. Since SFCACHE files are just used as a repository for files, you can not convert them to any other format.

If your file has nothing at all to do with a ReadyBoost SFCACHE file, but you do know what program is used to open it, Try looking for an Export menu or an option under the File > Save As menu, for saving the SFCACHE file to a different format.

More Help With SFCACHE Files & ReadyBoost

Please know that the sfc command is in no way related to SFCACHE files, so if you're dealing with the System File Checker in Windows, it has nothing to do with ReadyBoost.

Similarly, even though "sfc" is used in both, files that end with .SFC have nothing to do with .SFCACHE files but are instead used by SuperNintendo ROM files, Motic Microscope Image files, and Creatures Saved Game files.