Depending on the SSD model, it can work only in SATA I, although the Mini 2010 being SATA II-capable. Do some research about SATA III models which work in SATA II mode with the Mini 2010.
Samsung 840 EVO and Crucial M500, MX100 are known for being compatible with SATA II. PNY XLR8, on the other hand, downgrade itself to SATA I on SATA II buses.