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Two parts of your card card can have their running speeds altered.
1) The Memory.
2) The GPU.
ATITool offers you a way to do both, and an auto function that will do one (or the other) at a time.
The auto function should allow you to find the fastest running speed of each of these components.
If funny things happen like flashing parts of the screen or individual pixels showing up in obviously incorrect colours, then you have exceeded the maximum running speed of your component (under its present cooling system). Exceeding this maximum speed can cause lasting damage.
ATITool allows you to change the cooling characteristics of your GFx card - you can set the fans to increase speed earlier (or later) - if a fan runs faster it cools more - but its also noisier.
Why did i mention cooling above? Because better forms of cooling (e.g. water cooling) can allow you to overclock further becasue they dissipate more heat and therefore stop your card components from overheating. Heat is your probably your main enemy when overclocking.
Take your overclocking slowly, and use ATITools inbuilt Artifact Scanner to ensure you aren't going beyond the cards working capabilities. It will tell you when there are Artifacts (i.e. Pixels will show up as the wrong colour on the display, and it will warn you). If there are artifacts turn your overclock down a bit.
Remember - overclock too much and... BANG! New GFx required.
M
