Windows Vista Tip: Enable Any USB Drive To Work With ReadyBoost


vista.jpgIn the never ending quest to squeeze more performance out of your Computer, faster disk drives, more memory, and CPU upgrades are usually the popular path taken. With Windows Vista another option exist to enhance performance using a built in feature called ReadyBoost.

Vista ReadyBoost allows you to use a USB key as virtual memory in order to enhance performance. Unfortunately Vista has limitations on the specifications of the USB key that can be used with Ready Boost. If you have a USB key that Vista will not use, below is a work around to get any USB drive around this limitation.


ReadyBoost requirements for USB keys are as follows:

  • The USB Key must be at least USB 2.0.
  • The device must be able to do 3.5 MB/s for 4 KB random reads uniformly across the entire device and 2.5 MB/s for 512 KB random writes uniformly across the device.
  • The USB Key has to have at least 64mb of free space.

If your USB key is at least USB 2.0, but is rated slower for the random reads and writes required to use ReadyBoost, more than likely you have seen this message:


If so, plug in the USB Key, and cancel Autoplay if it pops up.

Click on Start button, and select COMPUTER. After Windows Explorer opens, in the right window pane find the USB Key you want to use.

Right click and select Properties, then select the ReadyBoost tab and uncheck Stop retesting this device when I plug it in.


Click OK and safely unmount the USB Key from your Computer.

Before Proceedingthe next step includes exporting the registry key to use as a backup if needed. DO NOT SKIP THIS STEP. As a safe guard, you may want to create a System Restore point when making configuration changes to your System.

Open the Registry (click on the Start button and type Regedit in the Run field).

Navigate to:
HKLM (Local Machine) \ SOFTWARE \  Microsoft \ Windows NT \ CurrentVersion \  EMDgmt.
Right click on
EMDgmt and select Export to back up the Key to a location on your Computer (you may also want to copy to a  CD or USB drive that can be accessed if needed).


Under EMDMgmt will list all the USB devices that have been connected to your Computer. Select the USB Key you want to use with ReadyBoost and click once on it (in this example I have selected the FIRELITE USB drive).

In the right window pane, modify the following values:

 – Double click on Device Status and change the Value Data to 2 then click OK.
 – Double click on ReadSpeedKBs and change the Value Data to 1000 then click OK. (after clicking OK, the value may be displayed as Decimal – 4096)
 – double click on WriteSpeedKBs and change the Value Data to 1000 then click OK.
(after clicking OK, the value may be displayed as Decimal – 4096)


Close the Registry when completed.

Plug your USB Key back in to your Computer, cancel Autoplay if it pops up, and go to Start \ COMPUTER and find the USB Key. Right click and select Properties, then select the ReadyBoost tab and you should now be able to use it with ReadyBoost.


Keep in mind, ReadyBoost benefit is to only enhance performance for random access reads and is used as a read-ahead cache program.

Enabling USB Keys that is rated slower than the specification required by ReadyBoost may not give you the performance boost you are looking for. Also if your PC is Dual Core and has 2Gigs or more RAM, you may not notice any performance boost when using ReadyBoost.

As always test first. Your mileage will vary.

Article Source Windows Vista Magazine written by Chris.

Filed under Windows Vista Tips by  #

Comments on Windows Vista Tip: Enable Any USB Drive To Work With ReadyBoost Leave a Comment

May 26, 2007

Al Myers @ 5:55 am #

My problem is that Windows Vista will not recognize ANY usb drive that I connect. It goes through the "new hardware" cycle and in the end tells me to contact the manufacturer for the latest driver. I am using new usb 2 thumb drives from different manufacturers as well as two SmartDisk FireLite drives which it also fails to recognize. I've searched but can't find a solution. Any ideas?

January 11, 2008

Matt Henson @ 1:16 am #

Thanks a lot this worked great. although I have to say I went a little further and by deleting a lot of the keys that were their. In fact I deleted them all. This way when i plugged it in their would only be one. It seems every time you unplug it and plug it back in with out unchecking the "Stop Retesting the device when I plug it in." box it makes another registry key for the same device. So i had a lot of duplicate keys their that I did not need. Once I did that and just worked you method with one key it fixed it perfectly.
The only issue i have now is trying to understand why it now suggest to use zero (0) MB for optimal performance. It use to suggest to use just under 4GB like 3820MB or something close to it. Not sure if it has to deal with the fact that I am on Vista x86 Ultimate SP1 RC with 4GB of RAM or not.
Now that it is fixed I think I might just not use readyboost. I read that it does not work well with more than 2GB of RAM.
Anyways Thanks again for this. I am going to keep a link to this post for future reference.

January 23, 2008

Jason A @ 6:21 pm #

This is brilliant

Bought a 4GB Stick and it wouldnt work on readyboost but now it does, thanks.


January 13, 2010

raymund @ 10:39 am #

i'm using windows seven starter, and thers no Dont retest box. any option?

March 3, 2010

Padraig @ 10:43 am #

For Windows 7 you have to also create a key(DWORD 32) "DoRetestDevice" and put it to "0"
Its because w7 is testing the usb drive everytime now and you have no option to disable it.

March 17, 2010

Jamie @ 2:29 pm #

This Wont Work for me, i follow all the steps it just doesnt work :{ any help?

October 3, 2010

jazz @ 11:40 am #

is there a way to Restore my usb back from readyboost…like when i use 3415mb of usb memory to ready boost i can get it back?

January 31, 2012

yall arestupid @ 12:15 pm #

y'all are stupid!!!

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