Overclocked GPU generates more heat from higher voltage intake and even if you can keep the temperature down, there’s still a higher voltage intake that pose a risk to your GPU. The graphics card is rated to work with a set of voltage range. Exceeding these limits through the process of overclocking increases the possibility of ruining the component to a certain degree, depending on the material and how sensitive it is. Overclocking, as a whole, is generally considered as a high risk-low reward type of investment. Plus this could void your warranty. So, unless you’re 100% certain that you’ll benefit from overclocking, I suggest you stay with the default presets.