How to overclock NVidia GT2xx and GT3xx

DO NOT USE EXTREME VALUES
AFTER YOU FINISH GAMING, I RECOMMEND RETURNING BACK TO THE DEFAULT VALUES.
1. Download and install Nvidia system tools from here
2. Open Nvidia control panel
3. From the left panel select performance and accept the agreement
4. From the left panel select performance - Device settings
5. From the right panel , under clock speed select custom and adjust the clocks as you want and press apply. For me 700/948/1540
6. Keep memory clock at max, increase the graphics clock by a 50, Keep the ratio between Processor clock and Graphics clock at 2.2 and use FurMark to check stability and temperature.
7. Make sure you select high performance power plan.
8. In FurMark, select stability test, Xtreme burning mode, and uncheck Full screen. Press Go! and monitor the temperature and performance. If you are satisfied keep the clock settings, change them otherwise, click Apply and check for stability.
9. After finish gaming i recommend you repeat the steps and select the factory shipped frequencies.

Enjoy!!