I tough the same thing, It only got that high once, after i installed about 30 gb's worth of games, but still installing 30 gigs of info shouldn't have bumped it so high. Well i guess il just keep a close eye on the fragmentation.
p.s. right now my pc will not let me try it.
because i just removed a ssd from my system recently.
I haven't looked for more info regarding Ready Boost, i gave up on finding more about it, atm i tough i could just get a second 7200RPM HDD, since my current HD is getting more and more data stored day by day, cause of my constant game installs XD.
I also searched the internet on that topic because i use it on my i-5 sandy bridge with 8 gb ram..tomshardware, wikipedia have an article bout this. As an 8GB user we cannot feel it like on the <2gb ram system. But you can actually monitor the read and write operations in the resource monitor or in the drive meter gadget.
but with an 8gb ram, superfetch is really good. and readyboost compliments the superfetch with extra memory. true sequential read/write of hdd is fast but random read/write is a lot better in flash memory.
on my first notebook toshiba satellite (dual core pentium, 2gb usable ram) i used it and in one case it add my winsat aero graphic assessment with +.1 dont know why maybe because of superfetch/readyboost.
just weeks ago i dedicated two flash memory on my new samsung netbook (atom with 1gb usable ram) and saw results. also in the winsat aero graphic asessment i found additional +.1.just have to repeat the test to cached it in memory.
and even here on sandy bridge i-5 notebook. i did the winsat test twice to improve the score by +.1. so i believe superfetch works (and make use of 8gb ram) and readyboost for random read/write during heavy disk activity.