Then how to unlock the GPU voltages are you guys talking about overclocking in hardware if yes then i have no experience in hardware overclocking original gpu become faulty so i will give it to a repair personnel until then i want to play some casual games so i put 9800GT instead surprisingly its providing exceptional performance in GTA5 still wondering if overclocking would be much helpful the GPU itself does not seems to be ancient only the small amount of RAM (512MB) is holding the GPU back
Core voltage allow GPU to generate even more headroom than it typically offer at default voltage. However, it is always risky for people who are new or doesn't know a bit about how overclocking can be done. So I'd advise you to avoid doing it. As for gaming performance, overclock rather unstable the GPU in games. Generally, with 100 to 200 MHz overclocking, the FPS boost will not be more 4-5, that too comes with added bonus; Crashes, BSOD, reboots etc.
. Therefore, risking your GPU for so little performance gain is mere stupidity.
I remember doing the GPU overclocking only for benchmarking purpose and never had done for gaming. Also, I'd recommend you to save some cash and get a better GPU so that you can enjoy the latest games.