GPU-Z is a free, lightweight, and standalone tool designed to give you detailed information on your graphic card GPU. It supports both Nvidia and ATI Graphic GPUs.
Just run it(no installation required) and it will detect your GPU instantly. The information for your GPU will be shown in a simple-to-use window. It displays some basic information such as GPU technology, size, release date, shaders, DirectX support, pixel fill rate, memory size, bus width, bandwidth, GPU clock, etc.
If you have multiple graphic cards installed, you can view individual graphic card details by selecting the card from the drop-down list.
Go to Sensor tab to get live details about your GPU’s Core Clock, Memory Clock, and Temperature.
Clicking the minimize button will move this handy utility to the system tray, you can choose to continue refreshing this Sensor screen while it is running in background. Enjoy!