How to manually trim an SSD in Windows 7?
Some SSD manufacturers have provided utilities on their websites that allow you to perform a "TRIM" like function manually. Check yours and see if it has that.
I wrote an article about TRIM; it also refers to a tool to manually TRIM your SSD: ForceTrim (download ForceTrim.zip, scan report at VirusTotal).
OCZ's forum is gone, but an archived version of Here's a tool to force-TRIM your entire drive is available. The source code is unfortunately lost.