Will a sata3 SSD work properly on a Mac mini (Mid 2010) with 2.4 GHz CPU?

Yes, you can.

Here are the theoretical bus speeds

SATAI - 150 MB/sec - 1.5 Gb/sec SATAII - 300 MB/sec - 3 Gb/sec SATAIII - 600 MB/sec - 6 Gb/sec

In theory, a very fast drive could saturate a SATA2 bus, but if it does, it will still send the data, just slower than it's capable of. If that bothers you, just buy a slower SATA2 SSD drive.

Regardless, you'll be very happy with the performance upgrade over a slower drive. It's the best upgrade investment you can make.

SSDs with SATA-X are backward compatible.

• SATA3 is compatible with SATA3, SATA2 and SATA1 connections
• SATA2 is compatible with SATA2 and SATA1 connections

I for example use a SSD with a SATA3 capability on a SATA1 bus. (Crucial m4 in MBP 3.1)

My advice: Always take the latest SSDs. They have a more refined garbage collection. It's also preferable to take a SSD with SATA3 in order to profit from the faster bus speed in case you use the SSD in another computer some day.