Now, start the Unigine Heaven benchmark in windowed mode so you can change the frequency while it is running. I generally use the Heaven benchmark as it's easy to run in windowed mode and artifacts are noticeable. Start with 100MHz OC and apply, then watch for any artifacts in the textures. These may be seen as flashing green, pink, or black textures. If none are present, push it up another 100MHz. Continue this until 400MHz. At that point, it will be best to go in 25-50MHz increments depending on the memory you have. Once you start to see artifacts or just crash, restart it and back it off 50-100MHz from the previous number and repeat the process of inching up until the same thing happens again. You will eventually hit a limit. I was able to achieve an 1010MHz (+505) overclock. Any higher and the Heaven benchmark would have wild artifacts and than crashed the computer a short while later. Once you have your magic number, write it down and set it back to defaults.