For SAMP, it seems as though you need a mega-super-computer graphics card to run it. Or, well. Something better than a GTX 750. I have an NVIDIA GTX 750 Ti and with basic modifications such as skin, weapon, and vehicle mods, I still struggle to keep a steady frame-rate, but this is mainly down to how compatible GTA SA is on the newer machines, seemingly. I can run GTA V better on this graphics card than I can run San Andreas, which is absurd on so many levels, but to be able to run it how I would like with an enb and a few other mods, I think I would need a GTX 960 at least.
That graphics card will not get you very far in terms of SAMP I'm afraid. I'm just talking from personal experience and how much of a pain in the ass it has been for me.