Question about SSD

Currently i have a 120gb SSD with my OS and Fallout 4 installed on it. My motherboard only has one SATA 3 port. I would like to purchase a larger SSD for more games. Instead of reinstalling my OS to the new drive id prefer to use the new SSD in a SATA 2 port. Obviously it will hinder the performance of the drive but for strictly gaming will using the SATA 2 port slow the loading times noticeably?