It's a GT 1030, not GTX which has much higher performance. Even if you double the voltage to 2.0v, you won't see much performance increase as you're limited by the GPU chip itself.
Also, most newer low and mid ranged GPUs are voltage locked, that means you can't go above a certain threshold even though the software might report the increase.
If you're interested in gaming buy 1050/Ti or better.
http://gpu.userbenchmark.com/Compare/Nvidia-GTX-1050-vs-Nvidia-GT-1030/3650vsm283726
If you have budget issues, search eBay or local shops for cheaper second-hand GPUs like GTX 960 (average 100$) or 950 (less than 100$) which is much cheaper. Get one with a long return time and stress test it with different softwares to make sure it works like a charm.
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You could gain some performance by highly overclocking the other components (GPU, RAM) if you haven't done so. But, do note overclocking them can be a pain as you will experience freezes and crashes all the time till you get it stable.