@ B.Gates, m.oreilly and Callsign_Vega:

When you installed the RST v11.x.x.xxxx drivers, did you take the original or a modded version?
How did you get the v11.x.x.xxxx drivers installed (manually from within the Device Manager or by running the installer)?
If you have a RAID array, did you test, if Trim is active within the array?