What Is an SFCACHE File Used For?

This article describes what an SFCACHE file is and how it's used by Windows, plus how it's different from CACHE files.

What Is an SFCACHE File?

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 can use for extra memory. It's normally called ReadyBoost.sfcache.

ReadyBoost is a feature first introduced in 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.

You can delete the ReadyBoost cache file from a USB device by disabling ReadyBoost. Right-click (or tap-and-hold) the device and choose Properties. In the ReadyBoost tab, select Do not use this device.

Enabling ReadyBoost

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.

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

SFCACHE vs. CACHE Files

SFCACHE files are similar to CACHE files—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 they are used only as a repository for files, you can't 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 file to a different format.

More Help With SFCACHE Files & ReadyBoost

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 images, and Creatures saved game files.