You have a GT 730, if it's the DDR5 model then I think realistically that's pretty good for that motherboard and the level of CPU you have. The DDR3 version is weak.
You can test this by using a program like MSI Afterburner to monitor CPU and GPU usage while you play your games. If the CPU stays lower than 85% or so, but the GPU usage is at or near 100% then you could use a better videocard.
If your CPU is at or near 100% all the time but your GPU usage is lower, then that means you won't benefit from a better videocard.
In any case, I'd recommend the GT 1030 as the most to spend on a system that old. It's a small card that uses little power, so it's likely to work with just about anything.