The NVIDIA GeForce GTX 280 is pretty overclockable. Best of all, NVIDIA provided all the necessary tools for easy overclocking, with complete access to core and memory clocks as well as fan speed. So, we just had to try overclocking it to see how far it can go! Like in our previous overclocking guides, we did not want this to be an example of extreme overclocking, where you would need to resort to third-party coolers. We wanted this attempt to come at "no cost" to the user. That meant overclocking the GeForce GTX 280 using its standard cooler. Link : NVIDIA GeForce GTX 280 Overclocking Guide
