I’m trying to use about 5GB a 64GB usb flash drive—already formatted as exFAT—for ReadyBoost on a 64bit Windows 7 machine, but the slider for space to reserve ends at 4094MB.

After 2 hours of Googling I haven’t found anything other than os or file system that would limit ReadyBoost to 4 gigs, but it’s not either of those.

What am I missing?

  • To my knowledge, 4 GB is the general limit on ReadyBoost. I think I remember having this difficulty before. Nevertheless, you may want to question your use of ReadyBoost. ReadyBoost is designed for computers with very little RAM (I think I had heard <1.5 GB was usually where it had the biggest effect) , and this may explain why the 4 GB limit is imposed. It is unlikely that anyone starting out with such a small amount of RAM would want to suddenly expand their memory so significantly. That being said, I don't know if 4 GB is a physical limitation. – fakedad Mar 26 '15 at 2:05
  • @fakedad: According to what I've read so far, 64bit versions of windows 7 and later are supposed to raise the 4GB limit to 32GB per device as long as the file system supports larger files. – tired Mar 26 '15 at 2:46
  • @fakedad This machine has 5GB of RAM, which is very little for how it's used; it's currently 10GB deep in pagefile. I know the real solution would be to get more ram, but i'm trying to be cheap and see what i can do with what i already have. – tired Mar 26 '15 at 2:57
  • There is a limit to the total system memory you can have if you want to use ReadyBoost. Why are you using exFAT that likely is the reason. – Ramhound Mar 26 '15 at 3:28
  • I would agree. NTFS is probably a better choice for a file system. – whs Mar 26 '15 at 3:38

Use NTFS. When using exFat my computer only recognized 4Gb of a 32 Gb SD card. Format your SD card using the NTFS (I did a full format, not quick format). Windows will recognize the real amount of your SD card.

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