Could have been the ssd, they are not created equally. A lot of the cheap ones are barely faster than a raptor, and you're right, a system with a lot of ram won't see as much of an improvement as one with say 2GB RAM.

My biggest plus to using an SSD is loading/hearthing/zoning in, it all happens much quicker on the ssd than it did when i used raptors, one velociraptor for my main wow folder and the OS, and another older raptor for the 4 alts.