You need native SATA 3 ports to do get the performance out of an SSD drive. If you motherboard is "older" you don't have them and SSD performance is capped... (list brand and model motherboard just in-case...)
Also, if you want to improve FPS in games SSD's won't help there at all (with or without SATA 3 ports....) System will boot faster, and levels will load a couple seconds faster.