May 1, 2008
Tip and Trick Editorial

ReadyBoost Not Working or USB Flash Key Stick Not Support or Enabled In Windows Vista SP1

ReadyBoost in Windows Vista uses a USB flash drive such as USB key or memory stick as additional memory to the operating system to boost system performance. However, after installing or upgrading to Windows Vista SP1 (and even in Windows Vista RTM), the ReadyBoost may stop working and no longer functioning, or saying that the USB flash key drive is poor in performance to run ReadyBoost.

The symptom is that when a USB flash drive is inserted and connected, Windows Vista is still able to properly detect the USB flash drive inserted, and gives an option to let user decide whether to run ReadyBoost on the drive. However, after evaluating the read/write IO speed of the USB flash key, Windows Vista judges that the USB memory stick is not good enough to use as ReadyBoost device, as the poor speed of the drive won’t improve any performance. The unsupported USB Flash storage device include even the premium quality (and priced) faster ReadyBoost approved USB key, and the USB drive can be used and work properly before upgrading to Windows Vista SP1.

The error in speed detection is probably due to USB problem facing Windows Vista SP1, which may have installed efficient USB drivers. As a workaround, the USB ReadyBoost key not recognized in Windows Vista SP1 (or Windows Vista RTM) issue can be fixed and resolved by tweaking the registry to force Windows Vista to recognize the USB flash drive as a valid ReadyBoost enabled device.

Firstly, format the USB flash drive to a clean state. Then run Registry Editor (regedit), and navigate to the following registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\EMDMgmt

There are a few branch keys (similar to sub-folders under EMDMgmt) available, which has the format similar to


Delete all this registry keys (folders) away. These registry sub-key values store characteristics and various information or settings about each and every USB mass storage devices connected to the computer, including portable hard disk, external HDD, memory card, USB memory stick and Flash key.

After deleting, re-insert the flash memory stick. If Windows Vista still unable to enable ReadyBoost feature on USB key drive that supposedly support Ready Boost, perform the following trick.

Re-open Registry Editor if you have closed it, and then navigate to the same registry key again:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\EMDMgmt

There should be a new registry sub-key created for the USB memory stick just inserted. Go to the new sub-key, and change the following registry values in the right pane to the following settings:


If the registry value name is not found, create a new DWORD (32-bit) Value and named it accordingly.

Close Registry Editor. The USB flash key is now recognized as ReadyBoost enabled. Right click on the USB memory stick drive in “Computer” to select “Properties”. Then go to the ReadyBoost tab and set the cache size and verify that ReadyBoost is working on the drive.

Pin It on Pinterest

Share This

Share This

Share this post with your friends!