Jekplex

My issue is my motherboard runs Sata II ports and all the latest SSDs are Sata III. From my knowledge I believe Sata III devices can still be runned by Sata II ports however they are limited by speed. Therefore my real issue is that I want a Samsung ssd. It can be one of three; 750 EVO, 850 EVO or 850 PRO. Now obviously it would be obvious to go for the 850 pro if i had sata III but I don't . Am worried that if I get 850 pro on sata II I will possibility get the same speed/performance that I would get with 750 EVO on sata II. Someone please help me with this, I don't want to be using more money then I need too with my current setup.

Would there be any problems if I ran a EVGA 500B with a MSI GTX 960. I'm only worried because I've seen on the box of MSI's graphics card, it's requirements are 42 amps and this PSU only has 40 amps. Will this cause a problem?

I have: Intel Core i5-2320 @ 3.00hz 1600x900 Monitor AMD HD 6670 GPU 450W PSU I'm planning on replacing the GPU and PSU with: Gigabyte GTX 960 EVGA 500w PSU I would like to know if this is a good upgrade and will i get any major bottlenecks when gaming. HELP!?