Yeah... I don't think so.
I've got 32gb ram, 256gb ssd and win7 doesnt have a problem using a usb stick for readyboost.
To my knowledge these are the only rules to enable readyboost.
The capacity of the removable media is at least 256 MB
The flash memory devices must be capable of 2.5MB/sec throughput for 4K random reads
The flash memory devices must also be capable of 1.75MB/sec throughput for 512K random writes
The removable media device should have an access time of 1ms or less.
Formatted as NTFS or FAT32 filesystem, both can make use a maximum of 4 GB of flash memory, which is the ReadyBoost limit.
ReadyBoost supports one flash device at any one time as of currently.
Full format and Retest the flashdrive. Then if it fails Open Event Viewer (Eventvwr.msc) and click the Applications And Services Logs category in the console tree on the left. Under this heading, click Microsoft, Windows, and ReadyBoost. Under this latter heading, select Operational. The log entries in the center pane include your performance test results.