as the motherboard is 4th gen (old) and low end.. will there be any performance drop??A PCIe 3.0 x 16 card will work in a PCIe 2.0 x 16 slot owing to backwards compatibility.
Be sure existing PSU is good quality and powerful enough (GeForce recommends 450w PSU minimum). If in any doubt about existing one or it's a cheap one, replace it.
as the motherboard is 4th gen (old) and low end.. will there be any performance drop??